Rear end swap- Anybody know trucks?

Going by the info it's most likely an 8.75, if it's on top of the leafs it could be a B body rear also, under the leafs it's a pickup rear.

I've found 8.75's in stranger places - found one under a '90 B van hightop conversion - the van was unmolested otherwise but had a 742 center and 5x5.5" axles.