The very first automatic transmission to work with a torque converter (rather than a fluid coupling) was the Buick Dynaflow, which was introduced for that 1948 model year. In normal driving, the Dynaflow utilized only the top equipment, depending on the torque multiplication in the torque convertor at lower speeds. https://gearbox-auto75284.blogitright.com/34274645/rumored-buzz-on-gearbox-auto