Richard : In regard to the "?" on the "S: in the picture Posted in your Reply #27 only signifies that this part was originally designed for use on the Thunderbirds. This Part was also used in 1967 on all Full Size Fords, Fairlanes, Mustangs and Falcons in 1967.
Your "?" should have been after the "B" as you forgot a "7" there. The Service Part Number was C7SZ-17B732-A.
Unfortunately, omissions are all too cmon with all of us.
Bob