I definitely need an alignment as i just replaced some steering and suspension components. My main concern is that if you look at my photos, one bottom fender lip is longer than the other.
That fender measurement may be a year change thing. I just measured the '71 Dart fenders on my Duster and they both measure ~8", but a '72 Dart fender I have here measures closer to ~7.5" like yours.
The rear dog legs have a similar changeover, the 72+ fenders are about 1" narrower in the dog leg than the 70/71 Dart fenders are. You might measure the rear dog legs and compare those as well, you may have a one of each type.