The first automatic transmission to use a torque converter (in place of a fluid coupling) was the Buick Dynaflow, which was introduced to the 1948 model calendar year. In regular driving, the Dynaflow utilised only the best gear, relying on the torque multiplication of your torque convertor at reduced speeds. https://gearboxauto62716.ampblogs.com/gearbox-auto-secrets-70831806