Physically, they will all bolt up and be functional but when it comes to timing marks, there are three separate covers, '68 (no cast-in timing marks/uses a bolt-on pointer), '69 (timing marks cast-in on passenger side) & '70-up (timing marks cast-in on driver's side). I remember mentioning this to Small Block last month and he was shocked to find out there were three individual covers. It's one of those things that is not absolute Mopar common knowledge.