Toyota A340E / A343F

Toyota's longitudinal four-speed — behind the Supra, the T100 and the first Lexus GS and LS.

It is among the most durable automatics ever built, and its reputation is the reason to know its name. It was strong enough that General Motors bought it as the 30-40LE for the Chevrolet Blazer and Isuzu, and it remains a common swap behind engines making far more power than Toyota ever put in front of it.

So a symptom on one of these is usually not the transmission. These are old cars now, and a slip or a harsh change is far more often the fluid, the throttle-position sensor or the vacuum modulator on the earliest versions than a worn clutch pack.

Where it does wear it is the overdrive clutch and the C3 (direct) clutch, presenting as a slip in fourth at a steady speed, or a flare on the 2–3 change. Both are much more likely on a unit that has towed, which is exactly what the T100 and the four-wheel-drive versions did.

The A343F is the four-wheel-drive version with a transfer case attached — mechanically the same gearbox, and the extra letter is the only place the difference is written down.