Well, see, if we get into the mechanical and electrical systems, I would say the next big divider after 67 would be '70 and insome ways '75 and particularly '76 are one offs. On the other hand not many '76 A-bodies made, so maybe we banish them to For F Bodies Only forum.
"In argumentation and informal logic, reductio ad absurdum (RAA) is a method of refuting a claim by extending the logic of the opponent's argument to a point of absurdity. Also known as the reductio argument and argumentum ad absurdum."