How to ID a CCKW carb

[JGilmore]

Strange the way this discussion has progressed...from "only carbs with sight plugs are true GMC" to "maybe there was one without"


Retro-roco wrote,

"....The first is 2135998, CARBURETOR ASSY. (Zenith 9778). It neither shows, nor lists the Sight Plug. The parts diagram is very similar (virtually identical) to the diagram you posted above from Parts Manual, TM10-1562 , 1 May 1943. The only differences that I note are the lack of a sight plug; and the throttle plate and shaft are rotate about the shaft 180 degrees (ie the shaft lever points down, NOT up. Now where listed is 2196082 Plug Sight Level.....the second carb listed is 213747, CARBURETOR ASSY. (Zenith Model 30 BW-11, Stock List #10046). It is noted as "NOTE: Following Carburetor not Used at Time of Publication." No where listed is the sight plug, GM-2178496.....


OK....let me make a little correction if I may.....

But first...You guys are using only half the numbers.....

GM part numbers are nice but you must use both numbers...GM and ORD. You will see in a minute why.....

Now..... the GM# 2135998 carb is not the first but the second....and the GM# 2137474 (cast iron) is the third.

The GM# 2103965 carb is the earlier one which was then superceded by the GM# 2135998.

Now, as I said......one should use both numbers when referring to parts because this may make a huge difference and tell a story.

Let's look at these carbs again with both numbers.

GM# 2103965 .........FSN # G 508-7002790
GM# 2135998 .........FSN # G 501-0131595

See what I mean? The FSN tells the tale here.

G-501 is , of course, a DUKW......and even though Paul thinks DUKW discussions don't relate to CCKW's..... this, as most engine changes do...does!

So the carb with the sight plug was developed for the DUKW..that's why it has a G-501 prefix.The ORD 9 for the G-501 notes that this carb used on " Chassis prior to 5900..." .... so this means from DUKW Chassis number 001 to 5899 this carb was used.
The parts listing and illustration clearly show the sight plug. The parts list also notes " This part is also used on Truck, 2-1/2 ton, 6 x 6 (GMC) (SNL G-508)

So ..if we want to date when the # 213998 die cast carb with sight plug was first used we must check the GMC documents on the DUKW production.

DUKW # 001 , motor # 270-121725 was the first DUKW but # 006 was the start of volume production so I would go with that date .....12/2/43.

This is when the die cast carb with sight plug started in motor production.


Jim Gilmore

Jim Thorpe, PA.

[retro-roco]

OK....let me make a little correction if I may.....

But first...You guys are using only half the numbers.....

Really? How do you think comments like that come off?? You chose to clip out only a portion of my posting (just like I did to you above!) and then tell me I'm posting the wrong and or incomplete numbers?!? Did you even read the first paragraph in which I cited the manual I was pulling numbers from? The manual that I was referring to doesn't have part numbers EXCEPT for the ones I posted, and certainly doesn't have FSN numbers!

Thanks for lending your voice to the discussion. BTW, just for the record, what manual are you referencing? I'm not in any way suggesting you're wrong, I'd just like to know your source(s).

[pfarber]

First off, I will always question myself and others till the answer if found. If GM had kept better records we could simply ask them... but several discussions with the GMC Historian and GMC Archives leads me to believe that to GM/GMC WWII never happened.

You are saying that the fuel level sight plug was not put on CCKWs until DECEMBER 2 1943 Or is that date supposed to be February 12, 1943?

"DUKW # 001 , motor # 270-121725 was the first DUKW but # 006 was the start of volume production so I would go with that date .....12/2/43.

This is when the die cast carb with sight plug started in motor production."

You need to connect a LOT of dots.

First I found:

"After it passed the Army’s acceptance tests, they ordered 2,000 production units. GMC started building them in Pontiac in November, 1942."
http://history.gmheritagecenter.com/wik ... %22Duck%22 This is from the GMC Historian. That 4 months earlier than your date (or 14 months... you really need to clarify that)

Was only one plant producing GMC 270? What about all the OTHER vehicles that used the GMC270? Staghounds (at least 8000 motors) come to mind.

How can you use say to use ORD numbers when they did not exist? Example, TM10-1562 which LISTS the sight plug by GMC number only. From my SNL-G508 cover page the ORD-9 SNL-G508 15 July 45 SUPERSEDES ORD 9 of 16 October, 1944. What does the 16 Sept ORD 9 supersede? I can look it up, but at some point we're inevitably going to conclude that:

The first SNL's came out late 43. Anything they list will not be an accurate reflection on previous parts books because the Army treated each TM release as specific to THAT contract. So if a later TM combined compatible parts, it was for convenience, not for historical accuracy.

The SNL (45) does not list ANY G501 number for the two fuel bowls I listed previously.

[JGilmore]

R-R wrote,

"...Really? How do you think comments like that come off?? You chose to clip out only a portion of my posting (just like I did to you above!) and then tell me I'm posting the wrong and or incomplete numbers?!? Did you even read the first paragraph in which I cited the manual I was pulling numbers from?...."

OK...I think I see what you are saying ...you are quoting an early TM and that it lists two carbs....the first one is xxxx and the second one is xxxx...

The way it was written it looked like you were saying one was the first and the other was the second...my mistake.

"....The manual that I was referring to doesn't have part numbers EXCEPT for the ones I posted, and certainly doesn't have FSN numbers!..."

Right...that's why a ORD 9 is very important to have. They will have more info then the early part books and have the all-important FSN numbers. If you do not have one I would suggest getting one as it will be a great help in identifying components.

".... just for the record, what manual are you referencing? I'm not in any way suggesting you're wrong, I'd just like to know your source(s)...."

ORD 9 SNL G-508, 15, July 1945 page 109.

Both the early die cast carb and the later die cast are listed. Also, I should have added although both are 28 AV 11 the GM# 2103965 carb is a Zenith # 9472 while the GM# 2135998 is a Zenith # 9778.

Paul wrote,

"....You are saying that the fuel level sight plug was not put on CCKWs until DECEMBER 2 1943 Or is that date supposed to be February 12, 1943?

"DUKW # 001 , motor # 270-121725 was the first DUKW but # 006 was the start of volume production so I would go with that date .....12/2/43....."

That was a typo on my part . Correct date for #006 is 12/2/42. This was the first DUKW delivered to the Army on the first contract. This was the closest date for the use of the GM# 2135998 - FSN # G 501-0131595 carburetor on production GMC 270 motors.

"....The first SNL's came out late 43. Anything they list will not be an accurate reflection on previous parts books because the Army treated each TM release as specific to THAT contract. So if a later TM combined compatible parts, it was for convenience, not for historical accuracy. ....."

Actually, the ORD 9 is one of the best sources for data on parts as it lists most of the parts used in CCKW/CCW/AFKW production from the early trucks to the later and gives FSN numbers for most of them. This is why the early GM# 2103965 carb is listed in it while it is not in Retro-Roco's TM.

Best is , of course, to have early and late parts books and cross reference them.

"...The SNL (45) does not list ANY G501 number for the two fuel bowls I listed previously..."

There are two fuel bowls listed for the die cast carb. # 2143816 which was superseded by # 2198543

Although they do not have a FSN number it is not uncommon in these part books for some parts not to have a FSN listed even if there was one assigned. Note that the body does have a FSN number...G-501-0124100 , indicating that it was the same as the DUKW carb.

A look at the ORD 9 G-501 (7/45) shows the GM# 2135998 - FSN # G 501-0131595 carb. It also lists the # 2198543 bowl and does not. as in the G-508 ORD 9, give a FSN number for it........however....the level sight plug...it is listed as G-501-0340660 - GM# 2196082 again indicating it was introduced with the DUKW G-501-0131595 die cast carb.

There is no reference I can find that shows the later die cast carb with a G-508 number.


Here is a clear YT&C photo of the die cast carb without the level sight plug on a CCKW.

Jim Gilmore

[pfarber]

Your linking the existence of a part with an FSN in supply and then with another vehicles production is not making any headway.

Pardon the caps: YOU COMPLETELY BLEW BY THE KEYSTONE OF YOUR OWN HYPOTHESIS!!!

"....The first SNL's came out late 43. Anything they list will not be an accurate reflection on previous parts books because the Army treated each TM release as specific to THAT contract. So if a later TM combined compatible parts, it was for convenience, not for historical accuracy. ....."

Actually, the ORD 9 is one of the best sources for data on parts as it lists most of the parts used in CCKW/CCW/AFKW production from the early trucks to the later and gives FSN numbers for most of them. This is why the early GM# 2103965 carb is listed in it while it is not in Retro-Roco's TM.


Yes, the SNLs are more detailed.. .they were designed that way, they had to cover multiple CCKW production changes whereas the TM10s had to deal with that specific contract.. I have a report that shows that the Army was desperately trying to reduce supply headaches and use common parts when possible.

We know that the CCKW didn't get FSN part numbers till late 43 with the appearance of the FIRST SNL-G-508. The only previous parts manual TM10-1562 1 May 43 does not use them.

I could only locate two SNLs for the G501... 1 OCT 44 and 18 March 45. And the only two TM9-802s I could find were 15 Oct 42 (2 months before they were even produced!) and 1 Sept 43.

I really don't want to get into a DUKW discussion. Please, connect the dots (and don't just list FSNs... the FSNs in the SNLs are not there to show any historical progression of parts.)

To me its seems like you are saying that any part without an FSN didn't exist prior to 12/42... that's doesn't sound reasonable.

And as I already posted.. the acceptance summary report does not break deliveries down by month, only year.

[JGilmore]

Paul wrote,

"....Your linking the existence of a part with an FSN in supply and then with another vehicles production is not making any headway...."

Um...you do know how the FSN works right? The vehicle it was designed or used on is usually the prefix. Ie...the bogie wheel seal for the M-4 tank (G-104) is the same as the seal for the M-3 light tank (G-103)...so it has a FSN number that starts with G-103 because it was the first vehicle that it was used on even though it was used on the Sherman too..

Same thing with parts that go to a CCKW or DUKW that were first used on a 1-1/2 ton Chevy (G-506 or G-83 GMC ) such as the GMC Pn # 477441 Front brake shoe LH link which is FSN # G-83-31-07980.

Because it was used on the 4x4 GMC first it has the G number of that vehicle.


"....Pardon the caps: YOU COMPLETELY BLEW BY THE KEYSTONE OF YOUR OWN HYPOTHESIS!!!..."

I don't know what you talking about here..can you explain further?


"...Yes, the SNLs are more detailed.. .they were designed that way, they had to cover multiple CCKW production changes whereas the TM10s had to deal with that specific contract.. I have a report that shows that the Army was desperately trying to reduce supply headaches and use common parts when possible..."


Yes that is correct but this just agrees with what I have said that the ORD 9 is a good source of data because of this very fact.


"....We know that the CCKW didn't get FSN part numbers till late 43 with the appearance of the FIRST SNL-G-508. The only previous parts manual TM10-1562 1 May 43 does not use them...."


Yes, that is why we must go the the ORD 9 to get the FSN numbers that help identify what vehicles they were from and when they came about.


".....I could only locate two SNLs for the G501... 1 OCT 44 and 18 March 45...."

18 March is a set of changes. What about the SNL G-501 dated November 1942? and the SNL-G501 dated Feburary , 1943 and the SNL-G-501 dated June 1943 and the June 1945 one sitting here on my lap?


".....And the only two TM9-802s I could find were 15 Oct 42 (2 months before they were even produced!) and 1 Sept 43...."..."


I thought we were talking part books ......these are maintenance manuals.



".....I really don't want to get into a DUKW discussion.... "


The development of the DUKW goes hand in hand with the CCKW..at least where the motor and powertrain are concerned. Other wise I would agree with you if we are talking about the chassis/hull etc.



".....Please, connect the dots (and don't just list FSNs... the FSNs in the SNLs are not there to show any historical progression of parts.) ..."

But as I have shown with the front brake links...the do indeed show a progression in many cases. First there was the G-83 GMC 1-1/2 ton 4x4...then later there was the CCKW. And because the link originated on the G-83 that is the prefix used on the part.

Want to know where the early horn (G 085-3301680) came from? Not the CCKW...but the G-085 Chevy 1-1/2 ton 4x4 bomb truck.

How about the early distributor (G 057-0152050) ? The GMC 4x4 1-1/2-3 ton Ord Maint truck (G-057) and the later distributor (G 501-015205) ...the G-501 DUKW.

I could go on and on....as I said the ORD 9/SNL are a good resource for determining the original on many, many components of the CCKW.




"....To me its seems like you are saying that any part without an FSN didn't exist prior to 12/42... that's doesn't sound reasonable....."


I am not sure what you are saying here... I gave the date or 12/42 as the start of the DUKW production and the later die cast G-501 carb. I did not say anything about FSN numbers having to do with that date just that it gave the ID for the G-501/DUKW.

Of course parts existed before the FSN numbers came into use. I said that using the GM number is only half the data and that the FSN (G) number is important to determine the origin of many components.


"....And as I already posted.. the acceptance summary report does not break deliveries down by month, only year. ..."


This is simply not so. When you say "the acceptance summary" what are you referring to?

I have a copy of "Statistical Work Sheets to 1 September 1945, ASF, OCD-D, E-M Div, R and P Branch" sitting here before me. It absolutely breaks deliveries down into months. There are other reports in the ORD files at the National Archives that give monthly totals as well.

All this aside I think we have proven that CCKW's used die cast carbs that did not have the level plug and about the time that they went to the die cast carb with the plug.

Jim Gilmore

[pfarber]

What other SNLs predate the existence of the vehicle by a month? Like the CCKW were there any production changes made that were not documented? Something had to be up if 3 months later they publish a completely new SNL.. That alone tells me that the first SNL must have had some errors/omissions.

You statements are all hinging on the belief that the FSN numbers can be used to 'date' a part. What Army publication dictates the use of a G506 or G501 parts book for finding G508 parts? Until Late 43 the ONLY parts books for CCKWs DIDN'T HAVE FSNs. How would a mechanic divine the FSN?

Now you are throwing in Chevy parts books?

Honestly, I think we are saying the same, thing, but using two different (and both are) theories to say the same thing. The fuel bowl sight plug came out in mid to late 42 (I maintain more mid than late) you, if I understand you, are saying its Dec 42 at the earliest. Yes, there were carbs that did not have the sight plug. I put them at about 10-15% of production.

My contention is that the FSN, being a made up number for supply purposes, has no relation to production dates. And using an FSN (even if cross referenced in another SNL) is not saying that's when it was put into production. The Zenith 97778 28AV11 carb predates the FSN, and unless you can dig up a PN for the carb WITH the plug, and one without (there are evidently two zenith fuel bowls for the same cab, with NO FSN) then we are really back at square one (and guessing).

I posted the text of of the TM9 that specifically details how to check the fuel in the bowl via the sight plug. Does the TM9-802 have such an explanation?

"(1) Remove float level sight plug from carbureter bowl (on engine side).
(2) If no fuel can be seen, remove drain plug from bottom of
bowl. If no fuel flows out, make check as itemized in (6) below.
(3) If fuel is level with sight plug hole, failure to start may be
caused by flooded combustion chambers due to excessive use of
choke, or by fuel not reaching the cylinder due to a dirty carbureter.
Check choke mechanism or remove carbureter and clean (par. 94).
(4) If fuel flows out of sight plug hole, carbureter float needs
adjustment (par. 94) or fuel pump pressure is excessive (par. 97).
(5) If fuel does not flow out of sight plug hole, but does flow out
of drain plug hole, check fuel pump for operation (par. 97) or check
adjustment of carbureter float level (par. 94).
(6) If fuel is not reaching carbureter as in (2), check fuel pump
operation; check line between fuel pump and fuel filter, clean fuel
filter, check lines between fuel filter and fuel tank."

And please post the OCLC number for this report that lists month by month production. Or scan in the pages.

[retro-roco]

Please remember, I'm a Chevy G506 guy, who happens to own just a couple of CCKW manuals. One of those is TM 10-1562, Parts List, 2 1/2 ton 6x6, July 1, 1942, Form X-142001. Ever wonder what the "X" stood for?? eXperimental like other military nomenclature??


As I mentioned before, it references the cast iron carb 2137474, CARBURETOR ASSY. (Zenith Model 30 BW-11, Stock List #10046). It is noted as "NOTE: Following Carburetor not Used at Time of Publication." No where listed is the sight plug, GM-2178496

The only reason that I mention this again, is to pose the question of whether the cast iron carb was ever ISSUED or installed on new engines without the sight plug. It would appear from the existence of the parts list in my manual, that they probably existed... at least in limited numbers for development. Is there any way to know? Interesting to note that at least for the diecast carb (28AV11), the change in fuel bowl design did not seem to warrant assigning a new part number to the carb?!?

[pfarber]

The cast iron carb was put into production in Feb, 1944. That's on a Tech Bulletin from GMC. The SNL from July 45 specifically states that the chassis #321078 is the start of the cast iron carb.

The die cast carbs weakness over rough terrain was known in 42, that's why they wanted a sturdier mount for the air cleaner. There were actually two kits made to help keep the die cast carb's air cleaner attached (one was the simple metal brace..this mod was done to my truck.. the second was a special bracket that allowed the new flat base air cleaner to mount to lip of the die cast carb).

Seeing the cast iron carb in a mid 42 parts book is not surprising, as most of 42 was spent 'standardizing' all vehicles to military parts... the 28AV11 was always (and still is today) a CIVILIAN TRUCK PART! You cannot find a carb rebuild kit for the cast iron carb that IS NOT an ordnance part... they were never put into civvy production post war.

Yes, there are two huge unknowns:

What directed the change in the 28AV11 carb to add the fuel level sight plug.
What date/chassis number/engine SN was it applied to?

I'm kinda hoping that it would have been mentioned in a copy of Army Motors. I only have 2 42 issue.

I emailed the manufacturer of Zenith 28 Series carbs (they are still made today!) and they had no reference drawings for the 28AV11. Their web site is http://www.zenithfuelsystems.com/

Could the 28AV11 carb be modified on the assembly line by YC/GMC? Someone had to tell them where to put the hole, and make a fixture to drill the fuel bowl boss. And why is there a boss even on carb WITHOUT the sight plug?

Reading through the TM9-1826C it does list two models for the 9778 - O-9778A and O-9778B. The carb id disk in my carb is 9778B, but the same PN as called for in the TM. The specs for the cabs are the same (jet sizes,venturi, etc).

The main thing that I am disagreeing with is the use of an FSN to date a part. J Gilmore is not posting scans of the pages, so we can only go by what were told... saying that you can't or won't scan in a document is not going to get you far. Put up or be quiet. We need to see the page, read the notes... maybe there is something that a person A is overlooking that person B notices.

I think now what I am disagreeing with is this:

The ASSIGNMENT of an FSN has no bearing on the date the part was put into production. FSNs are made up numbers used to simplify supply. Now it does coincide that the DUKW did start production in 12/43, and that the SNL (still, no example has been given... scan in a page from the 42 G501 SNL that shows the carb and its FSN) but DUKW production is not CCKW production. Yes, it was based on many of the CCKW parts, but then why didn't the TM10-1562 put out in May 43 ALSO list FSNs? By May 43 TWO G501 SNLs listing FSNs were written!

Both the 43 and 44 TM9-801 EXPLICITLY STATE to check the fuel level in the carb by removing the sight level plug. Its only implied in the TM10-1563 (on page D-3)

[JGilmore]

"...What other SNLs predate the existence of the vehicle by a month?..."

Are we talking about the DUKW manual? The date I gave was for the start of production/acceptance of DUKW's. There were DUKW's before that. The manuals were produced as part of the OSRD contracts. The OSRD was the entity that developed the DUKW and not ORD or QMC. The DUKW was based on the Ford developed GPA which was also a OSRD project.


"...Like the CCKW were there any production changes made that were not documented?..."

Not that I know of. BTW...the production changes for the CCKW were documented. I know the document but so far I have not found it in the National Archives...but I am still looking.



"...Something had to be up if 3 months later they publish a completely new SNL.. That alone tells me that the first SNL must have had some errors/omissions...."


I'm sure that there were most likely errors ...nearly all TM's have them....however the updated ORD-9 was done because of the changes in the vehicle in production and not because of errors.


"....You statements are all hinging on the belief that the FSN numbers can be used to 'date' a part. What Army publication dictates the use of a G506 or G501 parts book for finding G508 parts? Until Late 43 the ONLY parts books for CCKWs DIDN'T HAVE FSNs. How would a mechanic divine the FSN? ..."


Not all...there is other data..... but you are not understanding that it is us...MV collectors that need to "Date" any part. Any part that would be used on the CCKW but was developed and used on a prior vehicle will/should be in the ORD-9 for the G-508. Why would a mechanic need or even care about "dating" a part? It is we that care not him. You are not understanding what I am saying. WE look in the FSN numbers to find when a part was introduced not a WW II mechanic .

It is not the entire FSN number that helps us but the first part of the FSN number...the "G" number . The "G" number gives us the prior use of the part if it was not developed for the CCKW/G-508



"...Now you are throwing in Chevy parts books?..."


I never said anything about Chevy part books...just Chevy parts that are identified in the FSN number in the ORD 9 G-508.
I'm sure that you know that many Chevy parts were used in the CCKW, right?


"....Honestly, I think we are saying the same, thing, but using two different (and both are) theories to say the same thing. The fuel bowl sight plug came out in mid to late 42 (I maintain more mid than late) you, if I understand you, are saying its Dec 42 at the earliest. Yes, there were carbs that did not have the sight plug. I put them at about 10-15% of production....

Right!


".....I posted the text of of the TM9 that specifically details how to check the fuel in the bowl via the sight plug. Does the TM9-802 have such an explanation?..."

As I have over 3,000+ manuals in my collection I don't have them all on bookshelves. i will dig out the DUKW TM's this weekend and see what they say.


".....And please post the OCLC number for this report that lists month by month production. Or scan in the pages. ....."

I an not familiar with what a OCLC number is.....and to scan the pages would be quite a task as there are hundreds of pages . I will post one of them from the second quarter FY 1945 at the end of this post.


"....The cast iron carb was put into production in Feb, 1944. That's on a Tech Bulletin from GMC. The SNL from July 45 specifically states that the chassis #321078 is the start of the cast iron carb...."

2/12/44 for the DUKW...see how the changes in motors for DUKW and CCKW are very close together....


"..What directed the change in the 28AV11 carb to add the fuel level sight plug.
What date/chassis number/engine SN was it applied to?
I'm kinda hoping that it would have been mentioned in a copy of Army Motors. I only have 2 42 issue...."


I have them all and will look to see if it is mentioned.


"...Could the 28AV11 carb be modified on the assembly line by YC/GMC? Someone had to tell them where to put the hole, and make a fixture to drill the fuel bowl boss. .."

Not too likely. These vehicles were done on a fixed price contract and each and every change would have to have an Engineering Change Order (ECO) outlining the change and wether it was with or without obsolescence . To do this at YT&C would have been very costly.


"...The main thing that I am disagreeing with is the use of an FSN to date a part. J Gilmore is not posting scans of the pages, so we can only go by what were told... saying that you can't or won't scan in a document is not going to get you far. Put up or be quiet. We need to see the page, read the notes... maybe there is something that a person A is overlooking that person B notices...."


Did I say " I can't or won't scan in a document "? I don't think I did....I don't know which document you are referring to here.....You have the ORD 9 for the G-508 right?

I should say here that I don't have a job that allows me to be on the computer during work hours like some do. My time is limited and I post when I have the time.


"....I think now what I am disagreeing with is this:
...The ASSIGNMENT of an FSN has no bearing on the date the part was put into production. FSNs are made up numbers used to simplify supply. Now it does coincide that the DUKW did start production in 12/43, and that the SNL (still, no example has been given... scan in a page from the 42 G501 SNL that shows the carb and its FSN) but DUKW production is not CCKW production. Yes, it was based on many of the CCKW parts, but then why didn't the TM10-1562 put out in May 43 ALSO list FSNs? By May 43 TWO G501 SNLs listing FSNs were written!..."

Whew..that's a big sentence....Here's an example. If the ORD 9 lists a carb as a G-503-xxxxx and then states it was superseded by a G-501-xxxxx carb it is impossible for the G-501 carb to have been introduced before 11/42 in motor production as DUKW motor production was not started until that time . This then gives a starting date for this component.

Please note that I have said over and over that I am using the production dates for DUKW motors and some drive train components ONLY as the motors for the DUKW and CCKW were being built at the same time with combined motor numbers.

Jim Gilmore

[JGilmore]

Ok.....

I dug a bit in my files and think I have found a very early photo YT&C of the G-501- die cast carb with the sight plug. It's a little hard to see....

It is one of the pilot models of the DUKW's and shows what appears to be a die cast carb with the plug. Photo would be sometime around 10/42 to 12/42.

Jim Gilmore

[pfarber]

For some reason your posts are still needing approval.. I think that's a problem with the update a did a few weeks ago.. I try to check the board every day, but the delay is not intentional.. somethings not right in the phpbb software.

From the photo's I can't see anything of the sight plug. Its a good shot, but wrong angle.

From my understanding of the FSN system was to reduce the duplicate parts numbers (not the parts, just the number of unique part numbers for the same item) for the same item. Other than the first group (the G group, which did have 'categories') there is no rhyme or reason why they gave the part that FSN. Why would they spend the time to code all the G508 parts under the G501 category? Even by GMC's own system 'C'=41 'D'=42. My best guess is that the FSN committee started with the DUKW because it would have been the easiest to do. It was not bound to the earlier TM10s, nor the old parts book by contract system.

Even WITH FSNs, each branch would still have their own internal FSN codes (FSNs didn't become standardized until post war).

My guess (WAG at that) is to look at the October 42 issue of Army Motors. That was the issue that open cab CCKWs were shown. I have the August issue and there is a blurb about how the pics showed the truck stenciled wrong (see.. they cared about that stuff way back then!)

I have located the Summary Reports you mentioned. They are not online... but a copy is available in MD at the archives.

[pfarber]

"Whew..that's a big sentence....Here's an example. If the ORD 9 lists a carb as a G-503-xxxxx and then states it was superseded by a G-501-xxxxx carb it is impossible for the G-501 carb to have been introduced before 11/42 in motor production as DUKW motor production was not started until that time . This then gives a starting date for this component."

I think this is flawed. First, the FSN number could be assigned at any time, to any part. I agree that, when ORD started CODING parts for NEW MANUALS it used the more efficient FSN parts numbers. But the FSNs for CCKW use did not appear for another year (the first ORD-9 in late 43). So you would NEVER see a part coded under FSN G501 for a G508 part for another year after the DUKW was introduced.

Also, NO G508/CCKW TM ever mentions an FSN for parts (it does mention some supply items like anti-freeze, oil etc by FSN) but NO PARTS until late 43 in the SNL. When I perform a text search for G501 or FSN of the TM10-1562 May 43 NOTHING is returned.

It seems that it was more likely that as two GMC-270s rolled down the line, they are stamped with SEQUENTIAL ENGINE SNs. But one goes off to the left for installation into a CCKW, the other off to the right for DUKW. Once it gets put into a DUKW chassis, or into a crate for supply, at that point the FSN system would control the parts.

There really would not be a reason why the wouldn't be identical. Right?

BUT, that same carb could have been on engines for months. The TM10's for the CCKW never made that distinction. Its a PN-2135998 with OR without that plug. Now since that carb is magically given an FSN you can in no way date that as the START of that carb with that plug. At MOST you can say (if you have a photo) that the carb and fuel plug were in production in 12/42, but you cannot say that is the START DATE. You can only say that 12/42 is the START DATE FOR THE FSN assigned to the carb used on the DUKW.

[pfarber]

Another example. The new FSNs for standard oil filter bodies.

The FSN given in the SNL for oil filters bodies is: Senior - Strap Mounted (FSN 8-F-1440). Its the supply standard oil filter for engines up to 300Cu in. Its in the SNL, but not the TM10's or TM9s. If a GMC-270 oil filter body was replaced, you would never get the cool gray decaled body.. you get a standard black one.

The filters were 'FSNd' in late 42 by the ORD standards committee. While there ARE differences between the FACTORY oil filter body and the FSN supply standardized oil filter body, by your logic, if the FSN appears in the DUKW parts book (I have no idea if it does) then thats when this oil filter was installed on CCKWs? Because the FSN for the same part is in the ORD-9-G501 and G-508? That's a false statement.

The FSN was assigned to a part for nothing more than logistical convenience. The fact that its in the G501 SNL is because there were no updated contract TMs for CCKWs, and the G508 SNL was almost a year away.

While I agree that if the G501 SNL shows the FSN, that that's a good indicator that the FSN was 'active' in supply, and documented in use. But, GMC was the original parts source for factory trucks. They came with whatever YT&C or GMC put on them, under the GMC parts number. The TY&C or GMC woudl not have known, nor cared what they called the carb... as it was not supplying parts books (well, they had to comply with the new SNL format, not the per contract parts books).

[JGilmore]

Paul wrote;
"....It seems that it was more likely that as two GMC-270s rolled down the line, they are stamped with SEQUENTIAL ENGINE SNs. But one goes off to the left for installation into a CCKW, the other off to the right for DUKW. Once it gets put into a DUKW chassis, or into a crate for supply, at that point the FSN system would control the parts.

There really would not be a reason why the wouldn't be identical. Right?..."


OK, now you're getting it! Motors were built for both vehicles at the same time. Motor numbers were done in ascending progression , that is they may or may not have been in actual numerical order but that they progressed upward as motors were built.
If we have a staring motor number for a change and another that has the motor and date we can interpolate between the two and come up with a fairly close date for the other motor.

I'm only using the FSN prefix to determine the approximate date of the part or change to the part. If it changed on the CCKW first it would have a G-508 prefix. If it was used on the DUKW first it would have a G-501 prefix. That's all I am using the FSN number for. The rest of it does not help us determine vehicles/dates or uses.


".....BUT, that same carb could have been on engines for months. The TM10's for the CCKW never made that distinction. Its a PN-2135998 with OR without that plug...."

Yes, but I think I posted the Zenith part numbers for the two die cast carbs. They are two different numbers.


".....Now since that carb is magically given an FSN you can in no way date that as the START of that carb with that plug. At MOST you can say (if you have a photo) that the carb and fuel plug were in production in 12/42, but you cannot say that is the START DATE. You can only say that 12/42 is the START DATE FOR THE FSN assigned to the carb used on the DUKW. ..."

Well....I'm not saying that 12/42 is the start date for the G-501- carb's FSN number. I said that the G-501-prefix shows us it was first a DUKW part and the G-501 ORD 9 states that it was used from the first vehicle prior to chassis number 5900 (Pontiac plant) and from 66072 to 7231 (St. Louis plant).

So if it was first used on a DUKW then it would not have come into use until DUKW production started about 12/42.

Also the sight plug also has a G-501- prefix . If it came on the CCKW first it would have had a G-508- prefix. As with the carb it would have come in with the DUKW production.

It is the prefix of the FSN number that helps us.

Jim Gilmore