A-body Hemi box 4 speed

I'll guess that someone did a tailshaft/guts swap on the stock case

Its hard to think someone swap to Mopar A-body tail-shaft to use in Chevy or GM car, why swap when you going to modify to fit anyway? Swapping the tail-shaft must include swapping the main-shaft, it take more work than modify the transmission mount and cross-member, who does that?

Yet, check the assembly plant and the tail-shaft casting