340 Wedge?
Also in 1972, all the side marker lights changed to the externally mounted generic type that was used on many cars after that. In fact my 86 Laser XT has the same markers with the 72 model year embossed on them.
My project 71 Duster has no ridge on the original trunk, while my 72 Demon (project again) does.
I also seem to recall a 72 Petty Blue Duster I saw years back at a wrecker that had a different looking grill than the 70-71-72 Standard or 71-72 Sharktooth. I remember looking at it and thinking, what a unique grille. I seem to think it was a tin filled in type. It may have been off of something else, but the car was mainly intact, and all other trim (and longer tailights) were present. The frame was rotten, but I scored the decklid (with ridge) as an extra for my Demon.