Okeh, here y'go, the left hand giveth: You're right. The '60-'62 cars are different in a lot of ways to the '63-'66 cars, which in turn are different in a lot of ways to the cars made after '66. There; y'been heard. Feel better now?
Good. Hang onto that, because now the right hand taketh away: You're also wrong. The '62 cars have a bunch of one-year-only differences to the '60-'61 cars; the '63 cars have a bunch of one-year-only differences versus '64-'66; the '67 cars have a bunch of one-year-only differences versus '68 and later, the '73 cars have a sturdy batch of differences from the '74-'76 cars, and the '73-'76 cars are different in a bunch of ways to the '68-'72 cars. So either you'd have to argue that the discussions should be split up as '60-'61; '62; '63; '64-'66; '67; '68-'72; '73; '74-'76 (which is even more of a losing argument than the one you're pursuing) or you'd have to admit that you're just arbitrarily rattlin' yer keyboard (pretty sturdy case to be made).
And guess what: practically, it don't make no nevermind on here, nohow. You might have a point worth chasing if there were enough traffic in the Early A-Body subforum to make it difficult for people to keep up or cause individual posts to get drowned out, but there isn't; never has been. And there's a history of drawing the A-body discussion dividing line between '66 and '67, going back long before this board existed, back to the early-1980s start of the Slant-6 Club of America. It doesn't need messing with; it works fine, and…yer just gonna hafta cope, dude.
Speaking as a Usenet veteran with decades of experience arguing on the internet: sometimes it is best to just stop growling, drop the stick, walk away, and console yourself with your certainty that you're right and
everybody else in the whole wide world is wrong (hover your mouse over the panel for the second caption or you'll miss half the fun).