Two things, John, I believe you are right. Secondly I went to the Hamtramck Historical site and looked at the dealer books for 1966, 1967, and 1968. For 1968 it says Cleaner Air System, standard all models. For 1967 it says cleaner air package (mandatory Calif, NA otherwise or on Hemi). For 1966 it says Cleaner Air Package (mandatory Calif, NA otherwise). Sometimes I should take my own advice and do some research.