Yeah it’s tough to find one source of info for the 75/76 fender tag codes or any codes (since not all options are on the fender tag).
I’ve resorted to combing through many Mopar sites (A, B, C, E bodies) for fender tag codes to try to figure out what some of the later codes are for 75/76 as I was stumped for some of mine. Primarily emissions related are the really tough ones.