I am speaking of 66 and later A BODY SEATS HERE. Don't know about the pre 66 seats.
No button =1966
Button on the side of the seat back with METAL seat backs =1967
Button on the side of the seat back with plastic seat backs = 1968
Button in the center of the seat back about should blade height =1969-72
If the button is anywhere other than the 4 examples above they are not 66-72 Chevelle/a body seats.
I WOULD SUGGEST going to TEAMCHEVELLE.COM and posting this in the forum.I guarantee you %100 that someone over there will know what they are. There are a lot of knowledgeable people there.
Just DON'T insult a factory 400 block or they will attack you. :lol: