64.5 coupe with 170 6 cylinder. Pretty sure it is a c4 behind it and the transmission is getting weak. Slips badly in first gear until it is good and warm. I am searching for a core that I can rebuild and am not sure what to look for. Are 6 cyl and V8 transmissions different ? Are there bolt patterns I need to watch for ? I have a line on a 6 cyl with automatic transmission out of a Comet but the guy doesn't know what year it was. Says it has been laying in his shop for 20 years, never got around to doing anything with it. How do I tell C3 from C4 ? Any other things I should look for ? Thanks so much for any insight.