I had rust all the way around the rear window channel of my 73 Impala. This was due in part to the car having a vinyl top.
I removed the moldings and the vinyl top. The metal mouding clips were all rusted away, the stud the clips mounted on were gone, the window chanel was rusted out in several places.
The rubber seal holding the window in place only held at the top center for 5 inches. You could pick the back glass up at the bottom like it was a hatchback.
But the glass didn't crack. Fixed all the rust holes, painted the roof, had a window guy put the new seal in. Two days later I filled the entire channel with black silicone sealer , smoothed it out, spread some on the glass and the back of the chrome strips that went around the rear window.
Stuck the moldings on , let it dry and never had a leak or loose molding again.
========= Harryface =========
1991 Pontiac Bonneville LE ~_~_~267,300 miles_~_~_