69 Dart fiberglass fenders
it is hard to tell from so close up and the 69 Dart and the 70-72 Duster are different enough that I can't say yes or no and be fully confident with my answer - but, I do recall having mounted them right to the rad support on mine.. in fact I used Cleco fasteners and I know they were pushed through the support. Before the Cleco's I used sheet metal screws - this allowed me room for test fitting other things. Have you tried mocking in a grill to see if things fit? FYI - there is no such thing as a fiberglass part that simply goes in - they all require some adjustments - trimming and what-not.