If you have a 3.38 rear then you should look for an S10 truck T5 with a 0.86 OD gear. That will give you ideal highway RPMs at cruising speed. If you have the 3.90 rear then the 0.73 OD gear is best. 1988 and earlier S10 T5s are very hard to find but if you get one it is most valuable for the cable speedo connection on the tail stock.
The 1989 thru 1993 S10 T5 will also work but won't have a cable speedo hookup.
