Hi Jayde:
I'm not too good with GMC, but I can tell you that my '41 Chevy 3/4 ton has the same 6 on 5 1/2" bolt pattern on both front and rear wheels. AND has the same differential which I believe was unique to the '41 3/4 ton's. If you look you can see the 3 jam bolts and locking nuts used to hold the pinion bearing in place from the back side. This was typical for the 1/2 ton closed drive shaft. When Chevy went to the open drive shaft in the '41 3/4 ton they cut off the snout of the differential and went to an exposed rear universal.
