Dodge Dart Swinger: does 1973 rear bumper/lights fit on 1974?
For a '74+ Swinger you have to swap the entire tail panel to change over to the earlier bumper. It has been done though, check out the first page of this thread
Turning a 74 into a 72
You'd need the earlier bumper, brackets, tail panel, rear valance and of course the tail lights.