Isuzu MU / MUA / MSG

Isuzu's rear-drive manual gearboxes — the MU and MUA families and the MSG beside them — in the D-Max, the Trooper, the Panther and a long list of light trucks.

⚑ They turn up under other badges constantly. Isuzu was General Motors' light-truck partner for two decades, so the same gearbox appears in Chevrolets, Opels and Holdens with a GM RPO code on the build sheet and nothing saying Isuzu. Searching the Isuzu designation finds the service material; searching the RPO code finds an option list.

They are built for load and for poor roads, which is the whole design brief: heavy, low-geared, and tolerant of abuse. They are also noisy by modern standards, and gear whine on one is very often normal.

Their failure mode is wear rather than breakage — synchronisers first, usually second gear — and they are rebuildable with parts still available in their home markets.

The 4JJ and 4JB engine pages here cover what sits in front of them, and the pairing is stable enough that one usually implies the other.