Hold on, Dusters and Demons are 29, LM29H1 for a 71 340 Demon, VM29H1 for a 71 340 Duster I believe. There are rumors of Canadian 71 340 Swingers. Others know more about that than I do. Anyway, if it says LH23H1x------, seems like it would be from a hardtop Dart.
