66 cuda rear window

rear window.jpg

Question... the rear window gasket is in somewhat decent shape, however it does not seem to be tight enough to the roof line. I don't see any leaks on the inside, but I am concerned about the seal disintegration as time goes on. Should I replace this window seal, or just fill the gap with silicon??? These windows are hard to locate if it gets broken during the process. Let me know your opinions and advice. Thank you.