Check out this article gives you a little insite to the C4 http://www.mustangcentral.net/tech/c4.html
The site has some good information but there is also a list of the tags and their numbers with the information about where the transmission is found, make and model, and the engine it is used behind. I would have to convert my information to a text list in order to post it and I might go ahead and do that at some later date. Once the clutch packs are opened up I can pretty much tell you what engine it was behind and what you need to replace to make it work behind a V8. I am sure that others have kept records like this too and if we all combined our lists we would have a complete list of all the years and models of C4s ever made. There are "good" and "bad" servos for the C4 but does anyone know what makes a good or bad servo? servo# apply dia. Apply Area Apply Force at 200 psi A.......... 2.825...... 6.268............. 1253.6 B.......... 2.710...... 5.768............. 1153.6 C.......... 3.120...... 7.645............. 1529.0 H.......... 2.960...... 6.881............. 1376.2 K.......... 2.375...... 4.430............... 886.0 N.......... 2.560...... 5.147............. 1029.4 O.......... 2.460...... 4.753............... 950.6 R.......... 2.820...... 6.246............. 1249.2 W......... 2.375...... 4.430................ 886.0 Z.......... 2.500...... 4.909................ 981.8 The C, H, and R are the servos that are considered the best for high powered applications. The A servo will actually hold more than the R servo and will apply faster than the C servo but it is almost never used. Why? It releases as fast as the C servo which has the highest holding power of them all. The K, O, W, and Z servos are used by the factory in the low demand applications where a six cylinder 170 and 200" engine is used. The have slightly more than half the holding power of the C servo and should be delegated to the low hp and torque applications unless modified. listed in the order of decreasing holding power this is the way that the servos stack up: C, H, A, R, B, N, Z, O, And K with the other side being the amount of time it takes to release the servo when you want to shift into first or third. This is the order from the fastest to the slowest: R, W, Z, K, and all the rest tied for fifth place. What causes a flare when shifting from second to third? If the servo releases too fast for the direct clutches to keep up it will rev like it is in neutral until the direct clutches finally grab and hold. The more play there is the more pronounced the flare will be. So your valve body modifications have to match the servo that you have. The adjustment of the intermediate band has to fit with the timing of the shift and it has to be maintained. The amount of clearance in the clutch packs has to match the rest of what is going on in the transmission so that it will not drag but will apply quickly and cleanly. It takes a bit of engineering but it can be done. The information about the servos can be used as you see fit - it is in table format and for educational purposes and I offer it freely to the public domain. You will not often see this so when you do - if you want the information then copy and paste it to a file on your computer. Keep the bit about it being public domain so you don't get hasseled fo using copyrighted info. I will talk about how to make use of the four smallest servos in high hp applications at a later date you can make very good use of them but you have to be careful.
