Duster shells all the same?
Just wondering if 70-75ish gutted empty shells where the same besides tail light panel and rear bumper mounts?
Some differences I know of
Side Marker Lights (which mikedevore mentioned) are different for 1970-1971 and 1972-1976
Floor Pans (Late 74+) on cars that had Catalytic Converters
Rear Crossmember 1974+ on cars that had Rear Bumper Shocks
Tail Panel, 1970-1971, 1972 only, 1973-mid year 1974, Late 1974-1976 (late 74-76 are shaped different to match up with the 74+ Rear Crossmember, otherwise it's the same as the 73-74 tail panel)
Trunk Extension (Driver Side) on 1970 California Emissions cars and all 1971 Cars is different from the 1972-1976 Extension
Package Tray will be different on 1973+ cars ordered with the Fold Down Rear Seat Option (aka Hang Ten, Conver-Triple, Space Duster, etc). Package Tray will be different on 70-76 cars ordered with the Rear Window Defroster Option (will have additional cutouts for defroster vent)
Core Support Opening will be different (1973+) on cars ordered with A/C and/or a 26" Radiator
Firewall is different on A/C and Non-A/C models (1970-1972), Firewall is different (73-76) from the 70-72 versions of A/C and Non-A/C.
Roof is different on 1971-1972 cars ordered with the V3X Canvas Convertible Roof Option, Roof is different on 1973-1976 cars ordered with the Sunroof/Moonroof Option
Torque Boxes on certain High Performance models (usually 340 cars and 340 4-Speed cars), usually not found on regular base models.
I know I'm forgetting some stuff, but that's most of the differences you can find on a Duster throughout 1970-1976