[A Chopped Coupe]

I don't know about a Y block, but I'm pretty sure it would need sometype of adapter.................not sure.
What did they come in, well from 66 on they came in Dodges, AMC's, Pontiacs, Camaros, Mercury, Mustang, Galaxie................on and on.
Looking at the picture the tail shaft sure looks like a Ford, but without more information such as case numbers, number of splines on input shaft, it's kind of crap shoot. The mounting ears on any GM car would be farther apart than the picture shows....................you need more information to make a positive ID. Sorry