Are the Extensions the same across the entire line, 4-Dr, 440, 500, R/T, Superbee, Hardtop, Sedan and Convertible?
Well, for a 70 Plymouth, all the quarter panel caps are the same with the exception that some have holes drilled in them for trim (GTX/Satellite) and some do not (Belvedere/Roadrunner), but otherwise the same caps. I'm pretty sure a 68 Dodge would be the same way.