83GLT:

The rubber gaskets used on the early windshields have a habit of hardening and shrinking, then they let water into the glass channel and it gets absorbed by the adhesive in the glass.

You could go to the dealer and order a windshield and seal but they will probably just go to an aftermarket installer for the parts. If you are not concerned about the appearance of the window gasket being identical to the old one, I highly recommend going with a 91 or later windshield that does not have the stainless trim on the gasket. The later seals are silicone based rather than the old "pure rubber" seals that get brittle and shrink. Personally, I will never go back to the old rubber gaskets with the SS trim.

If you are dead set on saving the original windshield, there is only one way I know of getting rid of the fogging. This involves placing the windshield in a vacuum chamber at about 22 inches of vacuum for 24 hours, once the cloudiness is gone, the chamber is pressurized with nitrogen so that the moisture in the ambient air doesn't sneak back into the adhesive. Seriously, you should only consider this if your windshield doesn't have a single chip and a replacement costs more that $5K. I have only done this once and don't have the equipment to do it again. It saved a prototype car windshield that was a hand crafted one-off.

Seriously, a new windshield with late model gasket/seal should cost around $200 installed.

jorrell