Measure WMS to WMS on yours and the one with discs.
WMS means wheel mounting surface.
S10 rears are 54.25, some disc ones are 58, ZR2 ones are 62 inches wide.
If you use the disc rearend then get a speedo ratio adaptor like in this link.
Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4