The "S" was a package option. I think you could make an S without having to buy the "S" option just by picking parts options. The 1st gen S had a tach. That was about it for a "check if its real" test. Other than that, all other parts could be ordered up. On a 67 it may have an 032 (273-4) or a 367 (Formula code) on the fender tag. I think there may be something under the C too. possibly a 150 speedo.
