Borg-Warner T18 / T19

Borg-Warner's T18 and T19 — cast-iron four-speed manuals for trucks, in Fords, Jeeps and International Harvesters.

⚑ The T18's first gear is a crawler, unsynchronised and very low — around 6.3:1. That is the design and not a fault: it is meant to be selected at a standstill, and a complaint that it will not go into first while moving is the gearbox working as intended.

The T19 is the same box with a synchronised first and a much taller ratio, which is why the two feel completely different to drive despite sharing a case.

They are almost indestructible and endlessly rebuildable, which is why they outlived their vehicles and are still fitted to things they never came in. A surviving one has very often been moved at least once, so the input shaft and the bellhousing pattern are the first things to establish.

Borg-Warner's manual gearbox business became Tremec, which is where the later material and much of the parts supply now lives.