In 1967, there were two variants of exhaust tips used on Shelby Mustangs.
Shelbys with car numbers lower than 1600 used a two-pice welded tip, and Shelbys with car numbers higher than 1600 used a one-piece formed tip (the exact cutoff date for switching from the one-piece tip to the two-piece tip is not known).
Click on the link below for the tip that is appropriate to your Shelby.
