I'm with Phil on this. Slamming the doors.
I always told passengers, " DON'T SLAM THE DOOR"
Wouldn't it be buckled in that area if it were crunched together??? They are flat. Don't know??The compressing the point and then stretching it makes it crack at that edge.
I feel like I have body stress cracks.
I was going to ask if 2 door sedans did it too or if it was a hardtop only thing,if its hardtop only that would be my guess a lack of a B pillar and perimeter frame allows some flex there.I'm sure everybody has seen second gen F-bodies with a kinked roof between the side window and rear window,I've seen that happen from going over railroad tracks too fast.Just read where two door sedans don't crack. Slamming the door on ht i guess would be logical since not reinforced as much as sedan.
Lucky basterd!!!!Mine came from the cheerleader I had back in the day, layed some pipe in that back seat let me tell ya. By the way how is your sister