Short reply--I don't believe that these windows had "gaskets" in the sense of the front opening window around the periphery or front deck hatch. I am not sure what was used, but it was a butyl compound I believe. The material gets hot, and melts--and runs. If are not leaking, then it is cosmetic. If leaking, the window will. have to be removed, disassembled and then cleaned, bedded as in automotive windshield. I might consider the Dow 795 or similar glazing compound. It would take a lot of cleaning--and I would try one window first.
If you decide to go that way, please post it here, and I will give you some thoughts. It is tricky stuff to use properly. Well worth the effort--and dose not get sticky with sunlight and age.