Back Glass Re-Seal Abort!

ssba said
The rustout in those photos was caused by a cheap replacement vinyl top that was poorly preped and installed.
The original tops dont have that particular kind of backing and the vinyl was heavier and much better quality.
What you have there is a combination of California sun drying/ cracking a low grade vinyl and a nonwoven dacron backing that wicks/ holds water.
I'm not saying that factory tops dont deteriorate with age. The woven back fibers do get weak and tears easily once started. What your seeing there was not the factory's fault or even a fair comparison to how the originals normally age.
To the OP I wouldn't be very worried about the Ohio sun destroying your roof metal like that in the photos.
That was neglect more than any other factor.

I'm sorry, but you're mistaken. First, sun doesn't destroy metal, moisture does. Which is why solid cars tend to come from dry, hot climates and rusty hunks of crap come from wet, humid, and coastal climates.

Second, I tracked down the previous owners of that car and have accounted for a large part of its history. It's an original paint car that never had the top redone. None of the trim had ever been off that car, so the top couldn't have been replaced. Yes, it's definitely seen better days and it was certainly stored outside too long. But that was a factory top. And it wasn't the first, or the last, factory vinyl top I've removed either. They all looked the same. The one from the '66 Fury my grandfather bought new in '66, the one on my '71 satellite that still had the factory markings underneath it, and the one from that '71 GT. All the same, and all factory. Maybe my description was lacking, but I didn't see you there when I was pulling the top off that car.