Actual 65 and 66 Dart bumpers are totally different as far as looks go and I think the mounting holes for the brackets are different too. Will the ones from VFN fit - maybe if they don't have mounting holes already pre-punched but I kind of doubt it.
The 66 rear bumper is different then a 65...its taller and the lower valance pan is gone, I'm not 100% about the front, I'll look tonight, I have one of each.
Both bumpers are different. Also, the 66 has the backup lights mounted in the rear bumper, whereas the 65 has the backup lights incorporated into the taillights.