The original Mustang gas cap was Ford PN C5ZZ-9030-A. Due to apparent theft problems, Ford added a retainer strap to the cap to make it more difficult to remove. The new cap with the strap was Ford PN ...

If your car's gas filler is its hungry mouth, then its gas cap has to be its, um, mouth-cover? Pacifier? No, that's terrible. This analogy is terrible. The point is, interesting gas caps are rare, so ...

Editor's note: Wayne Liebhard's interest in '65-'66 Mustang dealer-installed options and accessories has resulted in one of the best collections in the world. We asked him to put his knowledge to work ...