1971 duster fender mounted turn signals

Not the same as far as I know. The 71 cuda might be one year only.
These look like the correct ones for your duster. They used this smaller version up through 72. In 73 the housing was fatter and less streamlined.
Mopar Fender Turn Signal Assembly Signals Pair Dart Coronet 71 Charger SuperBee | eBay

Be careful, there are some listed on ebay as 71 cuda but they are not correct. Just though I would mention if you are comparing.