1975 Dodge dart conversion???

Not a big problem at all as far as the sheetmatal goes. You just have to use the entire clip, including grille, bezels, etc. Watch for clearance around the parking lights in the grille.

The biggest problem will be the bumper. '75 has the shock-absorber-type brackets while '73 has "normal" bumper brackets and they don't interchange without fabrication to the mounting points.

No difference between the doors on the exterior. I did hear that the glass doesn't interchange in some years because of the mounting arrangement in the glass. The door sheetmetal is even the same between Sports, Dusters, Scamps, Swingers, etc.

I've converted 2 Dusters into Dart Sports.