1970 Duster 340 and 1970 Dart Swinger 383

Welcome, very nice Duster you have there (same goes for the Dart too), if you can find a broadcast sheet you may be able to decode some or most of it, there is a few sites around to help you try to decode Chrysler BC sheets or fender tags, or even someone here may know, lots of knowledgeable people hang here.