I’ve owned many blazers since I’ve been driving. All of them have had the rear hatch that squeak. To make a long story short on how I found this fix, I just cut to the end.

I found on my blazer, the rear support lifts have metal clips in the ends that hold them on to metal ball studs at both ends. The clips had started to rust and where grinding on the stud balls when the window hatch was down.

To fix it I had to remove the support lifts one end at a time and fill them with silicone grease. After reattaching them I wiped off the excess grease.

I sold the truck two weeks later but for those two weeks the rear hatch made no noise at all. If your rear hatch squeaks, try this fix. Post on here if it worked for you or not.