I have owned my S15 Jimmy since new. The back glass has always rattled. I adjusted the latch, used electrical tape. Adjusted the tail gate and any thing else I could think of. Well I had an idea in my head that if the catch in the tail gait was not so narrow that it could secure the glass much better. I measured the Dia. of the latch on the back glass and the opening in catch when the catch was in the closed position. The Dia. of the latch was 1/4". The Dia. of the catch opening is 5/16 ". However the end of the catch is narrower. I went to Home Depot and bought a 1/8ipsX 2" brass pipe nipple. The inside Dia. of the pipe nipple is exactly 1/4" and the outside Dia. was over 5/16". First I ran a 1/4" drill bit to ensure it was nice fit. Then I used my bench grinder to mill the outside Dia. untill the pipe nipple would fit inside the catch on the tail gate. Once that was done I used a dremel tool to cut the pipe nipple almost in half to allow the I/4" drill bit to enter and exit the remaining half without binding. I then cut the length of the cut away pipe nipple to match the width of the tail gate latch. I then used epoxy to secure the cut away pipe nipple in the catch of the tail gate. This eliminated 98% of the rattle. The last piece was to put a piece of tubing over the alignment pin (On the Glass). Attached are the pics. of the tubing on the alignment pin on the glass and the fitting on the catch. There is a little bit of grease on the latch that shows up in the pics. but the fix works great.

 

Nice fix for a very common problem

 

I've had this problem too, and it only seems to happen in the winter months. Must be the weather stripping contracting a bit due to the cold. I had no idea that it was even coming from the hoop latch until I read this thread. I would just spray lubricant over every hinge and latch i could find on the back and that would fix it for a few weeks until it came back again. I just got my truck rust proofed and that seemed to fix it but it won't be long before it comes back. I think I'll try the tubing on the weather stripping and some silicone grease.

Another squeak question: Do any of you notice a slight chirping sound coming from the rear suspension when you hit a bump in the winter months? It could just be the window but it sounds a bit different.