A body louvers

The project we are working on would fit Dusters and Demons, guess I haven't paid that much attention to the Dart's rear window if it's the same or not. Same thing with the fastbacks, I don't think what we are looking at would fit those. The thought behind the lower filler panel was because there isn't enough clearance from the trunk lid when it's opening to clear another louver panel, so my brother came up with the idea of the filler. The original louvers from the 70's had nothing there and it looks kind of odd.