I think they are not as rare as people make them out to be. I have seen quite a few 73 340 Dart Sports at shows and in junkyard pictures etc.I own a 73 Petty Blue 340 automatic Dart Sport with the factory crank style sun roof. Its Petty Blue with white stripes down the sides not the up and over stripe it also has the white canopy vinyl top, it has the hood scoop with the hood blackout a white bucket seat interior with the console,tuff wheel,inside hood release,fold down rear seat etc. As another owner said in this post these are extremly hard to find parts for as no one reproduces anything for the sunroof and NOS parts are super scarce.The guy i got my car from parted out a brown,black stripe sunroof 73 340 Dart Sport for parts for the Petty Blue car. As for exact production numbers maybe Galen knows??? I would think maybe at least 200 of them were produced with the 340 but a bunch more were made with the slant 6 and the 318.Still pretty rare by all means but i dont think its rare like only 30 built with the 340. Post some pictures of the car you are looking at to buy.Always good to see some more out there being saved.