I found some mention of this on a diesel forum, and I'm sure it's been covered here on DF but I'm not having any luck with search here.

I was tasked with fixing this rear door window that had separated from the body "hinges". I was a little surprised to find that the body hinges are nothing more than sheetmetal (although perhaps spring steel?) that flex slightly to allow you to open the rear windows.

I had an extra tube of Dow U428 urethane from rear glass replacement in a Chevy, so I decided to try this. I have no idea if the repair will hold once the urethane cures.

The owner had attempted to repair with....caulk?....maybe? This didn't make my life any easier

I found my OMT worked well to shave down the caulk and old factory urethane or adhesive. I deliberately left a paper thin layer of the old base adhesive because it makes sense to me urethane sticks better to that than bare glass, even though the U428 claims to be "primerless"

After cleaning the body "hinges" on a bench grinder wire wheel I elected to scuff the paint. I have no idea if this helps or matters at all -- I'm a metal guy, not a glass guy

The M12 caulk gun is awesome for urethane

Being only a metal guy, I didn't have any wood clamps with sufficient throat depth, so out came the big locking pliers. In the background you can see the driver side rear window weatherstripping out of place which often can contribute to the hinge separation, but that is not what happened here as the rubber was still in place on the passenger side

 

Well in a fit of sheer paranoia I left it clamped for almost 48 hours (45 if you're counting). Initial results seem promising. I opened and closed it several times and it's not falling off. I'm probably jinxing myself by posting now....

 

The urethane sealer used by the auto glass folks is some pretty tough stuff. Once it cures, you shouldn't have any further issues with that glass moving or falling off the frame.