ZF S6-650 Archives - Transmission Digest
Handling 6-Speed Heavyweights

The present trend toward larger and heavier-duty pickups has now brought the ZF S6-650 6-speed manual gearbox onto the scene. This 6-speed transmission was introduced in 1999 in the Ford F 250, F 350, F 450, F 550 and stripped-chassis models. It has been used behind diesel engines from 1999 to current production and behind gasoline engines starting in 2002 models. GM adopted the S6-650 transmission for use in its 2500 and 3500 heavy-duty pickups behind both gas and diesel engines in the 2001 model year.