ZF5 Transmission
If we rewind the clock, Ford motor company knew they would have to also compete with Chrysler and General Motors in the late 80s in the light-duty diesel transmission game and the t-19 four-speed transmission was replaced in 1987. The t-19 was replaced by the ZF five-speed made by the ZF Friedrichshafen group. This transmission was an industry-changer in ways. It sported an all aluminum case, five speeds with overdrive, sprung synchronizers and was a back-load transmission. Ford used the ZF5 transmission with both its 7.3L indirect injected diesel and 7.3L direct injected engine (Power Stroke). Ford utilized the ZF5 behind its diesel engines until the ZF6 transmission became an option in 1999. The ZF6 was a six-speed transmission, which was everything the ZF5 trans was and more. It featured one more forward gear and also had an all-aluminum housing. One extra feature the ZF6 had that no other light-duty manual transmission had was that it was equipped with an internal oil pump. This was to help dissipate heat from the friction of several constant mesh main shaft gears. It circulated oil to an external oil cooler in the front of the vehicle.