What's up guys, how's it going? I was wondering if anyone knows what numbers to look at to tell if the transmission in my 66 GTO is original or not. I have an M21 4 speed. I had it reuilt not too long ago and in the process I found that it is a date correct 1966 transmission but that still doesn't tell me for sure if it's the original tranny that came in my car out of the factory. I know there is numbers on the transmission somewhere (not sure exactly where). Is that number supposed to match any of the numbers on the rest of the car like the metal tag on the driver side of the firewall under the hood or the tag on the driver side door post?