2/20 LTZ build, slider, no visible frame crack yet and no signs of a leak, but with an asterisk attached.
Installed a A.R.E. cap on my truck and did not want to have to deal with the "potential leak" problem down the road, that has been running for 170+pages and still seems of no concern and unresolved by GM.
Afraid I would eventually get the dreaded leak and have to have the cap pulled and stored just for the window repair.
I did the Permatex 81730 flowable silicone suggested by another member in some earlier posts.
I had thought about regular viscosity silicone but decided on the flowable type to seep into every nook and cranny possible.
Modified the tip to be flat and to fit between the spoiler edge and the glass, with a hole on the bottom face and the end tip intact.
Taped up everything as Kclyatt described and added some tape on the vertical seams at the top of the plastic /glass because it runs everywhere, hence flowable.
Did 3 seperate applications about 3-4 hrs apart, across the entire top of the glass, starting in the middle and working to the left and right.
The separate applications allowed the silicone to set somewhat and allowed me to build up and fill the entire void to the top of the glass edge and down around the corners and down the sides for about 6 inches.
I think I used 4-5 of the 1.5 oz tubes and used the same modified tip on each tube during the application.
Have no idea if it has helped, but figured it was worth a shot compared to some of the leak repair nightmares that others have reported .
Think I will order some of that cord for the spoiler front seam that someone was kind enough to post a picture of and the Amazon link.
Good Luck guys and girls.