ive been told that the term comes from a string of parts stores [like checker or pep boys of today] only they were selling all makes of parts under the factory backed mopar brand name. along about the late 40's to early 50's a sherman antitrust action shut them down, due to the factory backing, chrysler only salvaged the mopar name on its own parts after that. this could be wrong as ive no verification for the story, cant even remember who told me. JEFF tucson az.