The TorqueFlite 999 is a Chrysler three-speed automatic transmission with an aluminum case and 23-spline output shaft. Various versions of this transmission have been around since the TorqueFlite’s introduction in 1956. It is most commonly referred to as a TF999 or 999, but it is also known as a TorqueFlite 6 (very early models), TF904, 32RH, and 30RH. An early nonlockup version of this transmission was used in Jeep CJs, YJs (until ’92), and some XJs, and later-model electronic shift units were used in late-model YJs and TJs until 2002.
All models of the TF999 use a planetary geartrain and a torque-converter clutch that engages in Third gear through a clutch solenoid on the valvebody. In late-model electronic-shift versions of this transmission, torque-converter engagement occurs when it receives sensor input from the PCM. Engagement is determined by coolant temperature, vehicle speed, and throttle position. Otherwise, overall operation, including shift timing and control, and early-model torque-converter engagement, is hydraulic.