‘71 Demon at Mecum $70K lower estimate

What is the deal with charger wheel openings? I'm curious because when I was restoring my Demon I spent a few days researching front fenders because the wheel lip was different than the rear wheel openings. The duster rear body simply got the dart front clip bolted on. It looks odd to me now that I am aware of it.
Dusters and demon shared the quarter panels. Fits both.