These rears will work but wont hold up to serious power...The Ford 8.8 rear out of a 96-2001 ford explorer are the most affordable option for 350+ hp engines.If you are dead set on using the s10 rears here is some very useful info I found....   GM made two housings that came in these trucks, the 7.5/ 7.625 and the 8.5, both of which are ten bolts. The 7.5 has more of a squared  shape to the cover and straight axles tubes that measure 2 3/4" whereas the 8.5 uses a round cover and the axle tubes step down from 3" to 2 3/4" near the leaf pads.

2 wheel drive width from WMS to WMS is 54.5 inches
4 wheel drive width from WMS to WMS is 59-60 (depending who measures it) inches

S10 Rear end Ring Gear and Axle Sizes:
1983 to 1992 7.5" ring gear 26 spline axles
Available from 1988+ 7.625" ring gear 28 spline axles
Available from 1995 and up, 8.5" ring gear 30 spline axles, standard for 98+ ZR2's with rear discs