Aisin AL6 (D478)

Aisin's six-speed manual for Jeep — in the Wrangler JL and the Gladiator.

It is the current answer to a long line: the Peugeot BA-10/5, then the Aisin AX-15, then the Mercedes NSG370, and now this. Four suppliers across four decades in one model line, which is why a Wrangler manual question must always start with the model year.

It is a new gearbox and its pattern is not yet settled, which is worth saying plainly rather than repeating what is written about its predecessors. What is established is that the complaints are about the clutch and the hydraulics — a bite point that has climbed, or a pedal that stays down when hot — rather than about the gearbox.

The concentric slave cylinder is inside the bellhousing, so a leaking seal is a cheap part behind an expensive job: replace it whenever the gearbox is out, whatever its condition.

A crunch into every gear is the clutch not releasing, which on these is the hydraulics far more often than the plate.