The Turbo-Hydramatic (THM) series was developed to replace both the original Hydra-Matic models and the Buick Dynaflow. The first G.M. transmission to hold the moniker was the Turbo-Hydramatic 400, first used in the 1964 model year in Cadillacs. Now available primarily, in many forms as rebuilt transmissions. The Buick version, which followed shortly thereafter, was known [...]