1973 Dart Sport 340 Sunroof question????

Help...I have a line on a 1973 Dodge Dart Sport. It is a factory 340, auto car, w/AC and a sunroof....fold down rear seat and it looks like a somewhat narrowed rear end(??). Anyone know the production on these 1973 Sunroof 340's? It is rough and needs a lot but straight and all there. Latest Mopar Muscle has a 1973 Duster featured and it says about 50 produced for 340 Dusters in 1973.