I got my glass from ChevyDuty and it installed without too much difficulty - mostly of my own making. The roll down windows had no frame that PickleBus is talking about - just the track at the bottom. Piece of cake. The "glass setting tape" (more like a cloth gasket) fit just fine, and that oil works even if it is counter-intuitive.

http://www.chuckthetruck.homestead.com/page14.html