66 and 67 A and B body seats are the same, but the tracks are different. Remember that if you’re buying anything but 67 A body seats. The 67 tracks are the same as 68-69 A body, but a decent set will set you back at least $300
66 had height adjustable tracks, 67 were solid. The back part of the seats is also different on 67 A vs B bodies, as the chrome strip is wider on the B.