How to Identify C Transmissions on a Fordby John Stevens
The "C" family of Ford transmissions was one of Ford's most popular class of transmissions for more than three decades, and includes the C3, C4, C5 and C6. The C4 and C6 are held in higher esteem by automotive enthusiasts than the C3 and the C5 for their durability and simple designs. Aside from the C6, the remaining C-class transmission are very similar in appearance, which can made differentiating between then challenging upon first glance. However, there are some simple ways to tell one C-class transmission from the others without disassembling them.
Raise the vehicle with a floor jack capable of safely lifting and support the weight of the vehicle, then lower the vehicle onto jack stands.
Climb underneath the vehicle, between the front and rear tires, to access the transmission.
Examine the bell housing. The front end of the transmission, where the transmission attaches to the back of the engine, is called the bell housing. The bell housing gradually tapers down in size from the back of the engine to the center, or "body," of the transmission. Look for a seam between the bell housing and the body of the transmission. If no seam exists, the transmission is a C6. If a seam does exist, it will be necessary to inspect the oil pan to determine whether the transmission is a C3 or a C4.
Determine the number of bolts used by the transmission's oil pan. The transmission's oil pan attaches to the bottom of the transmission with several retaining bolts, which are located around the entire lip of the pan. Count the total number of oil pan retaining bolts. If the pan uses 13 bolts, the transmission is a C3. If the pan uses 11 bolts, the transmission is a C4 or a C5.
Measure the length of the transmission's bell housing with a measuring tape to determine whether it is a C4 or a C5. The length of the transmission is defined as the distance between the front of the bell housing and the seam that separates the bell housing from the body of the transmission. If the length measures 7 inches, the transmission is a C5. If the length instead measures 6 1/4 inches, it is a C4.