The rear window of my 23 coupe seems to be loose. I am hopping that someone could share a picture of that for reference showing the correct installation . Is there a moulding around it on the inside and outside that keeps it tight and secure?
Sounds like the rubber channel that goes around the window is rotted or broken out. The rubber channel is available from the T parts houses.
The window is installed from the inside. Remove the sheet metal trim moulding and remove the glass to put the rubber channel around the window.