Aisin 03-72LE (A44DL)

Aisin's light rear-drive four-speed — in the Mazda MX-5 NB and the Suzuki Vitara and Grand Vitara.

An MX-5 and a Vitara sharing a gearbox is the kind of thing that only becomes visible once the designation is established, and it roughly doubles the literature for both.

It is a small, simple transmission and its faults are age rather than design. The solenoids and the valve body account for most of them — a harsh or delayed engagement into drive, a change that arrives at the wrong speed, or a limp mode — and all three read as terminal on a car this old and usually are not.

On the MX-5 the commonest complaint is not a fault at all: four ratios in a light sports car means the engine is busy at motorway speed, and there is no fifth gear to be missing.

Fluid is Dexron and its history is unknowable on most surviving examples; a pan drop tells more in ten minutes than any amount of scanning.