Does your car have a pillar between the windows on the door and the windows for the rear passengers? I know all of the auto manufacturers went to different styling in the 70s with "opera" style windows for the rear seat in a 2 door car. All you have to do is look at the mid to late 70s 2 door Delat 88s, 98s, Cutlass etc. Not to mention other manufacturers. A few that come to mind with unique windows are the Chrysler Cordoba in the late 70s (check out the movie Anchorman for a good example), the Ford Thunderbird, and the Mercury Cougar. Ultimately, I think it is just a styling thing.
Hope my $.02 helped.