Isuzu S101 / 5LM60

Isuzu's manual gearboxes in the Chevrolet S-10 and GMC Sonoma — the four-speed S101 and the five-speed 5LM60.

A Chevrolet pickup with an Isuzu gearbox is what the GM–Isuzu partnership left behind, and it is why an S-10 manual can be one of four quite different things: these two, or the Borg-Warner T-4 and T-5. Four suppliers in one model line means the year and the engine decide, and a listing that says only manual settles nothing.

These are light-duty gearboxes and their failure is the usual one: second and third synchros, crunching on a fast cold change, then the gears. A crunch into every gear is the clutch not releasing, which is hydraulic and outside the gearbox.

The linkage wears before anything inside does. A change that has gone long and imprecise is the shifter's own bushings, at a fraction of the cost of opening the case.