Starting in '88 with the 4.3, chevy had the 7 5/8 rear (you have the 7 1/2). I don't know if the '89 and up 2.8 had it or not. The ZR2's have the 8 1/2 rear that is 4" wider than normal S10's.
Never did it, but I'm pretty sure the 7 5/8 is a direct bolt in (assuming same ratio) and with the 8 1/2, you need some drive shaft mods.
I wanted to be a follower, but all the leaders seem to be lost.
The full size 10 bolt and the one in the ZR2 are the same 8.5 ring gear. This is the desirable of the 10 bolts. The newer 7 5/8 88Blazer is talking about is common in all newer S-10's. Its kinda a hunk o junk. In fact i heard from a GM mechanic they (factory) installed the wrong gasket on the rear diff and it does not get oil to the ends of the tubes the way it should. Don't know what years tho. Not many aftermarket parts available and I havent found a compairable axle in width to swap yet. Its 52 inces wide from back plate to plate. I think the ZR2's is 54" and is the perfect length.. Any one know of a good cantidate with no cutting of tubes??