My 1972 F7 Dart Swinger
regarding seat frames: when doing the seats for my 1970 Dart, I needed the bottom springs and frame for the drivers side and found them offered new from OER. They were a perfect match for the broken frame and blown spring on the originals. They were listed for a 1970-71 Challenger. Those complete seat frames and springs are currently listed from Classic Industries for $360 a side - a real bargain. They also offer the seat latch/release mechanisms. I THINK that these are the same bucket seats for your Dart, different models having different foam resulting in different shapes. It's at least worth exploring.