The side windows and the windshield should have the gasket which have either a removable lock strip, or a section of the gasket which folds into and under the section next to the glass.
All if the ones that I have been around for years have been the lock strip style. You can tell this design by the metal cover piece which is usually at the bottom center. It goes where the ends of the lock strip meet. Pull the lock strip out carefully so that you don't tear it. Then I run around the edges to make sure that the glass isn't stuck to the outer flange of the gasket. Then start pushing the glass out , starting in one of the upper corners. Work the top out carefully and it will fold out of the gasket.
On these trucks, you always leave the gasket in the truck during removal, and put it in place before the glass. The older trucks, '72 and back, were the rope in style.
I was taught to clean the gaskets with penetrating oil to help soften the rubber. Same for the lock strip.
The side windows should be slide into the front and bottom of the gasket at the beginning of installation, work the front upper corner in some, you won't be able to get it all the way in, just be careful. Then work the back in and across the top.
I use foaming glass cleaner for lubrication. I also have one of the nylon tools to pull the rubber out over the glass, or the slider frame.
Reapply glass cleaner as needed, it will help, and the clean-up is easy.