Extended cab window noise

[1978steven]

From what I have found is it is not always the latch itself. The way the window is sealed into the door sometimes starts to separate from the door. I had this issue with my '01 and while riding in the back I could hold the latch like you did and what it was doing was simply pulling the window assembly tighter into the door. I noticed a decent amount of movement while doing it, so after getting it back home I did the same test but in the driveway. This time when I did it I could visually see the window assembly especially the weather seal area tighten right up into the door. Luckily a buddy of mine works at GM and helped me with the pulling of the window and resealing process. Not saying it's not the latch, but it's something else to look at to further troubleshoot...