Duster quarter windows

Not 100% sure if this is the reason or not. I read in one of the Mope mags about the "clandestine" development of the Duster by Plymouth, and one thing they mentioned was the radical curvature of the glass in the new design. I think they said that getting the front windows to roll down required some major thinnin' to make it work. Maybe they just didn't have the time or money for more thinnin' to make the backs go down.