I ran across this youtube vid and he stated the kit came from classictruckglass.com. I looked them up and they have a power and manual version (I prefer manual) and it looks like a nice kit but I cant find any threads about people who have used them so dont want to blow almost $400 and have buyers remorse. Also I'm correct that there is no difference in GMC or chevy windows right, since they only list them to fit chevy.
https://www.youtube.com/watch?v=8msKGodzYHI
http://www.classictruckglass.com/ind...it-manual.html
I like the wing windows in these trucks but I also love to drive with window down and arm on the sill, the windows are currently bit small for me to lay arm up there in comfortable position.