installing a vinyl top on a non vinyl top car

Check out this auction, those are the clips that go on the ends. Depending on what year your car is it may use these in all locations. You can certainly use them in all locations if you want. The change was made to those spot weld studs because it was cheaper. I dont like the weld on studs simply because the metal tends to rust around the stud.
Barracuda Duster Dart Valiant vinyl top clips nuts

These are the type of plastic clips that go on the weld (or screw) in studs. The trim slides over these clips.
75-85 NOS Chrysler Body Side Belt Vinyl Top Moulding Molding Trim Clips 10pcs R | eBay

Sorry I cant help with measurments. I have a swinger, not a duster. However the trim will attach the same. Good to see another vinyl top fan. I love vinyl tops on some cars. I think Darts look great with them. Dusters look good with or without. Im not too keen on the half top though.