Father-Son 1974 Duster Project
DD - I have used Flowmaster Delta Flow Mufflers a couple times and love them. On my 74, 8 inch wide wheel with 4 inch backspace and BFG 245-60-15 fit perfect and fill out the wheel wells. Usually on the you can go with a 255-60-15 with 4 1/4 and be ok. Measure to be sure because your rear looks a little different