I bought all of my weather stripping for my 73 from the dealer that I was working at in 1988. I never opened it until maybe 2014 or 15. When I opened the boxes, they looked all cracked and distorted. I bummed out and purchased aftermarket . When I finally finished the car in 2017, I unboxed the GM weather stripping and laid it out flat for about two weeks. I ended up looking perfect, so I sold all of the aftermarket stuff.