The primary automatic transmission to implement a torque converter (instead of a fluid coupling) was the Buick Dynaflow, which was introduced for your 1948 design yr. In standard driving, the Dynaflow made use of just the major gear, relying on the torque multiplication on the torque convertor at decreased speeds. https://gearbox-auto21851.mpeblog.com/59816101/a-review-of-gearbox-auto