The 1st automatic transmission to work with a torque converter (as opposed to a fluid coupling) was the Buick Dynaflow, which was introduced for that 1948 design year. In regular driving, the Dynaflow used just the prime gear, counting on the torque multiplication on the torque convertor at reduced speeds. https://gearboxauto65285.blogdomago.com/33040436/the-gearbox-auto-diaries