1973-74 Duster seats
Yes, the back seat will pop right into your dart in place of the factory one. THe only diference is that the lower section is not as deep as your factory one by a few inches, and the upper section is an inch or so narrower overall. Looks fine in the car, and no one will be able to tell the difference unless you swap out seats from dart seats to duster seats before their eyes to show them the difference.
Dart seats however, will not fit in a duster (owing to the small size differences i just mentioned)
Oh, and by the way, the seats in this ad are beautiful, and a screamin deal for all 3