Dodge Demon Rear Seat Compatibility?

You can only use the rear seat from a Demon, Duster, or Dart Sport. The rear seat from a Dart is a different shape/height. There were a few minor changes for the later years like small indents for the seat belt retractors, but those would be pretty hard to notice, so any year should work as long as it's a Duster, Demon or Dart Sport seat. Unless it's from a car with the fold down seat or "space saver" option, those require a decent amount of work to swap to a non-fold down seat car.