Help identify a 3/4 ton rearend

[Yellow Cheyenne]

I am parting a '72 Chevy Longhorn 3/4 ton pickup that has what I believe is a non original rear end. The rear axle has 1/2" studs that are smaller than what the front discs have (9/16" I think). The rear housing also has some paint left on it as opposed to the rest of the under carriage.

Both the front and rear of the center section can be removed. The rear cover has 10 bolts in it and is basically smooth. The front is cast iron and I believe it also has 10 bolts holding it in. It is a full floater set up. The pinion input can be unbolted from the rest of the front cast iron piece. The only numbers I could find on it are on the front left side of the cast iron piece and the numbers are 3834635. Can anyone help identify this piece? Thanks in advance.