Look up the door window regulator and it shows 1967 thru 1969 as the interchange. It also interchanges on other cars besides the convertible and goes up thru 1972. It doesn't make sense why the window is different.
Here is what I got bill for the regulator, part # 2765792 and 2965793 ds and ps for 68 and 69 as well as val's cuda's and darts. Take a look at the pics below. the one with my finger in it pointing to the "stop" is a 69 cuda vert door..glass is clear as well as straight across the bottom. 2nd pic with my finger and tinted glass also has a "stop", but there is a hump on the bottom of the glass, this is 69 fastback and is unique to 69 fastback.3rd pic is of the same glass. 4th pic with no stop, not quite sure what year it is from, but im betting its fastback...still gotta do some deciphering...its either 67 or 68. I dont have a 67 parts book. Sorry for the blabbing here, but in short for whatever reason it looks like in 69 they added the extra stop in the main glass....for what reason I dont know. Also 69 vert glass is flat across the bottom, no hump...I would like to see pics of 67 fastback glass, as well as 67-8 vert glass. Confusing as heck, but considering fastbacks were unique cars, thats why there glass is specific too.....the saga continues....
