Passenger side mirror 74 Duster

standard
Mopar Mirror RH LH Set 67-76 A-Body 67-70 B-Body Dart Demon Duster Charger NEW | eBay
sport
Mopar Chrome Sport Rallye Mirror Set Pair 70-76 Dart Duster Demon 70 SuperBee | eBay
FYI, the standard mirror on passenger side was not common and not offered on all years/models. So, finding a nice used one could take some time.
Note - those are just the first examples that came up. Not a recommendation to buy.