From what I remember Jody (Troublemaker427) is right as the only difference in 63 I know between AFX and SS was the tire size. Thats why at first the Chevy 409 Z-11 cars had to run AFX or Limited Production they called it as NHRA said they did not build enough for SS so all they had to do was use the bigger slicks. Rules were alot different back then as I believe in 63 you could not change the cam in the SS cars as you had the run the cam they came with. You could not use the cheater cams with a ton of duration at the same lift. It seemed from week to week different cars would be faster back then but it was a cool time. Ron