We are in the process of restoring a '65 Fastback that was originally equipped with a C4 automatic. Since our previous restorations have all been 4 speeds we don't have much experience in this particular item.
The transmission in the car is marked C6DP7006-A. I believe this means the transmission was out of a '66, possibly a Falcon as indicated by the D. The car we are working on has a build date of February '65 so I'm guessing that the transmission we need should have a casting number starting with C4 or C5. My question is what exactly should we be looking for in terms of casting numbers. Was there such a thing as a ZP which would indicate Mustang or were they more generic and used in several different models?
All Ford (including Mercury) cars and trucks use items developed and designed by their own engineering product line (Fairlane, Falcon, full size Ford, Comet) and can use without change, parts or assemblies from others. The Mustang line did not design an automatic transmission but used a design developed for Falcons. (The first engine designed for Mustangs was a Boss 302 in 1969.) The design activity for transmissions uses a code "P" hence the C6DP. Each design activity has a code in that spot, E for engine, F for fuel as in carburators, W for rear axles, etc. When the part is taken over by the service department for dealer use it gets a different part number (usually) that has a "Z" where the "P" was entered. Mercury uses a "Y" and Lincoln uses a "V" (I think). That "Z" part number is what you will see on most Ford service parts on the box.
Keep in mind that the part number you are looking at is the casting part number only. It is a part, no different than a nut or bolt. It does not have any indication as to what internal parts are used.
I think the correct casting number should be either a C4 or C5 part number (you are working on a 65) and that may be dependant on when the car was built. The more important thing to look for is the casting's date code. The next item is the transmission's assembly date code. To determine this (in a perfect world), the casting date should be earlier than the transmisson assembly date (by a week to a month) which should be earlier that the car's scheulded build date (by a week to a month).
Jim
Jim