I was taking apart one of the rear French cast/built split axle I got off of the old French dumper I had.
It seems that either they modified the axle flange or that this is a way to reclaim/repair the axle flange when the bolt holes get out of round.
First pic is the conical insert:
Second photo is the hub stud with the insert on it to show how it fits:
And lastly here is the axle flange with the insert fit into it. The axle flange hole is significantly larger that standard to fit the insert and bolt.
The SNL does not show this part, nor do the later ORD-7s (Stock allowances) does not list this either.
So I'm on the fence as to what it is: A post war/NATO improvement or a way to repair worn axle shaft flanges. I have not gotten to any other axles off the dumper to see if they all had it, or just this one hub.