This link shows how to lengthen the wheelbase of a shortbed s10 to make it work under a 47-54 Chevy Truck.
As for s10 rear ends:
2wd rear ends are 54-3/8" wide
4wd rear ends are 58-3/8" wide
ZR2 rear ends are 62-3/8" wide
(Measured wheel mounting surface to wheel mounting surface)