Peugeot BA-10/5

Peugeot's five-speed manual — in the Jeep Wrangler YJ and Cherokee XJ, which is as unlikely as it sounds and is the whole reason this page exists.

Chrysler bought it from Peugeot when AMC needed a five-speed and had none. It lasted five model years and was replaced by the Aisin AX-15, and it is the gearbox Jeep owners warn each other about.

The complaint is genuine and specific: it was not built for the torque in front of it. The 4.0 straight-six overwhelms it, and the failures are third and fourth gear synchros, then the gears, then the case. A BA-10 that grinds and jumps out of gear is at the end of its rating rather than badly maintained — the same story as the Tremec T-5, at a smaller scale and faster.

The standard remedy is a swap to the AX-15, which is a well-documented conversion precisely because so many of these failed. A Wrangler YJ of these years with a healthy five-speed has very often already had one.