I’m not exactly sure which years are notched, I know my ‘74 was so the assumption would be 73-76. But maybe not all of them depending on the retractors.
The later ones that are notched work just fine in the earlier cars, so the notched ones should fit all years of Duster, Demon and Dart Sport. The earlier ones that aren’t notched won’t fit the later cars if you have the original retractable belts. If you don’t they may still be an option.