Sorry, but no experience on a 66. However, I do know that early 70s A-bodies do have adjustments to move the glass front to back, to tilt the top of the glass in or out, and to move the glass up or down in the front or back. Best item to have is a factory service manual. If not, then take your time and study all the attaching points for the glass and the tracks that the glass rides in. The adjustments are "hidden" in the attaching points, not easy to see but they are there.