yup they are a different part number but the only difference is the inner flange that goes to the trim on the convertible VS non convertibles. For 63-66 darts and valiant cars. Is it really worth the extra $100.00 or so for the inner flange of 1.411(oops remeasured and it 1.435 , forgot to zero the measuring device) flange vs the 1.132 for the difference though? it has been discussed extensively over on Slantsix.org and even here by a few people. And my mistake is the convertible is 1.132 all sides (old gasket) vs my sedan @ 1.439 top and 1.325 side(old gasket)hardtop(old Gasket)@1.440/1.330 hardtop @ 1.41 all sides(new precision gasket)