HM290 / NV3500 (GM)

The five-speed manual in the GM full-size SUVs — the Chevrolet Tahoe and GMC Yukon.

It is the NV3500 under an earlier name. Getrag designed it, GM called it the HM290, and New Venture Gear took over production and renamed it — so a Tahoe's gearbox and a Sierra's are the same unit and their parts catalogues do not say so.

It shares the NV3500's most consequential quirk: it takes ENGINE OIL, not gear oil. A conventional 80W-90 ruins the synchros, which are designed around a much thinner lubricant, and the result is a gearbox that grinds into second and third within a few thousand miles. A great many have been condemned for what was a fluid choice.

Its own recurring faults are the shift tower and its detent springs — a lever that flops or will not stay in gear — and second-gear synchro wear, which is where the miles land in a vehicle driven in traffic.