How do you identify a c4 versus a c5 tranny. My Bronco is a pan-fill with the bump on bottom of pan and the new one I bought is a case-fill flat bottom.I always thought I had a c4 all these years! My torque converter and bell housing on the 302 are much bigger than the new tranny bell housing and TC.. I've read that you should stay away from c5's but don't know why. C5's had a locking torque converter. I should've done more homework before I bought this new tranny! I'm going to try to find some casting numbers. What is a good tranny shop to call for help? thx

Look up in the sky tonight and if you see a viper light your trannsmission woes will end.

Most likely you have a stock Bronco pan-fill C4. C5's didn't come out until '82. You can't really tell the difference by looking at them. You can check the casting numbers to be sure. A C5 has a casting number starting with E2. The major differences between a C4 and C5 are the converter (you can't get a C5 converter anymore) and the valve body. The C5 does have some improved parts and a better oiling system. Every C4 I build gets those oiling system improvements. A C5 can be built with a C4 converter and valve body.

I use case-fill C4's for internal parts only and only if they're '71 and newer. Rebuild the pan-fill C4.