it will bolt up and fit.....but the wheel opening arch is inward on the dart....whereas the duster is outward....here is a duster fender where you can see how the lip is different
plus the radius of the arch is a little different.....see how at the dog leg the duster comes more straight down whereas the dart comes back more.....so this fender is only correct for 1973-1976 darts and 1973-1976 dart sports