The relevant page from my Polara/Monaca FSM is identical to the one I posted from the Dart.I have never seen that setup on a c body before...........
The two factory part numbers I have for it are;
2534347 Spring
2260709 Seat
I haven't been able to locate any sources for it though.
View attachment 37515

Good job but I think that will cost you points on a concourse show lol.
-1 pointa backward return spring