Jatco RE4R01A

Jatco's longitudinal four-speed for Nissan — in the 300ZX, Maxima, Navara D22 and Pathfinder.

It is one of the more durable automatics of its era, which changes what a symptom means on a car this old: a harsh change or a slip is far more likely to be fluid, a speed sensor or the throttle position sensor than a worn clutch pack.

The throttle position sensor is worth naming, because on this transmission it does more than report load: a drifting TPS makes the gearbox change at the wrong road speed, or hunt between third and fourth on a light throttle, and it is very often diagnosed as a transmission fault. It is an engine-bay part.

Where it genuinely wears it is the direct clutch and the overdrive band, presenting as a flare on the 3–4 change under load. Heat is what gets there first — these were fitted to vehicles that tow, and an auxiliary cooler is a preventative measure rather than an accessory.

Fluid is Nissan Matic-D, and these predate sealed-for-life entirely, so the interval was specified and is simply often skipped.