The 1st automatic transmission to use a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was released for that 1948 model year. In usual driving, the Dynaflow made use of just the best gear, depending on the torque multiplication in the torque convertor at lower speeds. https://gearboxauto75296.blogs-service.com/65019346/a-review-of-gearbox-auto