Right?
Honestly you can see I was skeptical in the thread I linked, but then I realized I had a few of each 70/71 and '72 so I just measured. I don't know exactly when the change over occurred, you'd think it was probably at the same time as then side marker change but with Ma Mopar you never know.
Either way the 72+ fenders have a longer wheel opening, which makes the tire clearance at the lower front corner easier on those cars. If I ever paint my car I will take a "pie" out of that lower front fender to match the '72 measurements and grab some extra clearance on my 275's. They don't rub as it is but they definitely don't have much extra if I ever went to a slightly taller tire.
This thread has more measurements in it, the OP had a '72 with one fender of each type of wheel opening on his car. Didn't get a reply on whether both fenders appeared original, but the front section on the '70/71 fenders is 8" long where the '72+ fenders are like 7.25". The rear dog leg also got 1" narrower on the 72+ cars. Also worth noting is that the AMD reproduction fenders seem to match the later, longer opening. I can't seem to find the thread where I got that info though.
Help: 72 Dart Swinger front pass. fender rubbing
The front change is really helpful, the rear one just kind of exposes more of wheel well and corner of the chassis which doesn't actually look as good IMO.