Rear window seal

[Ridgeline]

I got a small leak in the upper right hand corner of my 87 El Camino. It came from California and has no visible rust anywhere. Does the back window have a rubber seal or is it glued in?

 

[85 Cutlass Brougham]

It is glued in using urethane adhesive from the factory. Over time, it can tend to lose it's adhesion with the paint it is stuck to, and start to leak or rattle. I would take it to a glass shop and have them cut it out and reseal it to the truck(car?).