73 DART SPORT REAR BUMPER

That is correct. 1973, no safety bumpers, but had the buggy bumpers. 1974 + had both I believe.

Ah, good, so you do understand that you just can't bolt the '73 bumper up to the '74 shock mounts. Using the '73 bumper either requires making a set of intermediate brackets to go between the shock mounting location and the regular '73 brackets to use the '73 bumper, or welding up and reinforcing the tail panel to match the earlier cars and using the '73 brackets. Getting the '73 bumper on is relatively easy, making it look factory requires a decent amount more work.

This thread has the most info, plus links to my build thread where I swapped mine over 1974 Duster rear impact bumper(remove,reinstall bumper without it)

And I apologize, I do not have a '73 rear bumper. Shipping would probably be prohibitive if I did considering the distance.