The plastic window is prob toast. The UV rays wreck the plastic. Unfortunately you can't replace the window without removing the top so you might as well replace the top too. I had someone replace my window and remove and reinstall the old roof which was a mistake.
. Bob, Thanks for the info on the top. The top is old but in near new condition (third one) and has been inside, undercover in AZ for the last 20 years. I do not want to replace it at this time. I do not know how bad the window is until I try to clean it. If it's not too bad after cleaning I will drive it until I need another top. I have pulled the car (numbers matching, 400, 4spd, vert) out of storage and I am working on a few issues so I can enjoy it again. I am the 2nd owner and have owned it for 50 years Shirl Dickey