I need a little help. I have a 66 that was originally a 6 cylinder. It now has a 302/C-4 combo. The problem is that I don't know if it has an original C-4, or if the engine/tans combo was slipped in complete. I can't find the I.D. tag on the trans. Is there some tell-tale way to find out which one it is? I need to know because I want to order a shift kit form Summitt and they list two different ones for two different spans of years of production. Thanks in advance for any help.