1966 - bolt in bows, lock separate from the handle in the lift gate.
1966 - Mid Year 1969 - bolt pattern along the windshield correlated to the vacuum wipers
Mid Year 1969 - 1977 - bolt pattern along the windshield correlated to the electric wipers
1966 - 1967 - Weather stripping around the lift gate area had square corners
1968 - 1977 - Weather stripping around the lift gate area had angled corners
1966 - 1967 or 1968 - the stakes that slide into the quarter panels are short and stubby (maybe two inches long)
1968 or 1969 - 1977 - the stakes that slide into the quarter panels are long and are much more likely to scratch the paint upon removal and install (around six or eight inches long)
Chrome window and drip rail trim available in various years depending on Sport, Explorer, and Ranger packages
I wouldn't be surprised if there were other differences, but those are the ones I know of.