I have the same problem with my '87. Mines cracked about halfway up on each side of the rear window. I've considered a fiberglass repair but there's not much surface area for a repair of the fiverglass and it would be difficult to get to the back side. Even new ones are cheap. I hate the though of having to have the paint matched as mine has great original paint but I've not found an alternative yet.

 

I just don't have much money until I pay off my Jeep. And I'm usually working. So it's not like I can just drive there every weekend.