Wheelbase is 116" but you probably want the track width - anywhere from 58-62" across mounting flanges. 1st gen. S-10 is 58", the 4x4 rear end is a bit wider than the 2x4 and is still too narrow with stock S-10 rims. You'll want 5-6" wider than the stock width, which you should be able to make by using wheels with less backspacing (3" instead of the stock 6"). Definately go with the newest S-10 rear you can buy if you go this route. Off the top of my head, early models used a 7.5" and then moved to a 7.625" in '87 or '89. I think they're up to an 8.5" in some of the models now.
Might be worthwhile to check out the 3rd gen. F-body rear ends as well (62"), especially if you can find one with rear disk brakes. You might have to use a lot of backspacing with that rear.
[ January 22, 2003: Message edited by: Stinkin_V8 ]</p>