How to Identify a C-6 Transmissionby John Stevens J.D.
The C-6 transmission is a heavy-duty three-speed automatic transmission manufactured by Ford Motor Company. The C6 was almost exclusively used for high performance vehicles and trucks. The C6 is often mistakenly identified as a C4 transmission, also manufactured by Ford. Not only do both transmissions have a similar appearance, they are both three-speed units. Because the C6 is more durable than the C4, it is usually the more expensive of the two, and can be harder to locate. Therefore, knowing how to identify the C6 is vital.
Count the number of bolts which hold the transmission's oil pan to the transmission. The oil pan is located on the bottom of the transmission, and uses a total of 17 bolts to hold the pan to the transmission. The bolts are located around the entire lip of the pan. Counting the number of bolts is necessary, as the pan for the C4 transmission uses a total of only 11 bolts.
Locate the drain plug. Whereas the C4's drain plug is located on the bottom of the transmission's pan, the drain plug on the C6 is on the side of the pan, and can be located on the driver's side of the transmission.
Determine whether the transmission's bell housing can be detached from the transfer case. Unlike the C4 transmission, which features a bell housing that can be separated from the transfer case, the C6 is a one-piece unit, meaning that the bell housing cannot be removed from the transmission. The bell housing in located on the front of the transmission. The torque converter sits inside the bell housing. If a seam exists between the bell housing and the center of the transmission, the transmission is not a C6.
Locate the speedometer driver gear. The speedometer driver gear on the C6 is located on driver's side of the extension housing. The extension housing is the rear portion of the transmission where the driveshaft enters the back of the transmission.
Locate the control levers. The control levers connect to the shifter inside the vehicle, and change the transmission's gears when the shifter is moved. There are two control levers on the C6. Both control levers are located on driver's side of the transmission, just above the transmission's pan.
- Motor's Auto Repair Manual, Ralph Ritchen, 1968.