[Stepper86]

The bottom end of the frame holding the glass has a bolt welded/soldered to it. This bolt goes trough a spring, and a bracket that is attached to the outerframe of the ventwindow assembly. A nut holds it all together.
If you want to take the vent window assembly out you need to remove:
1. Door panel
2. The bottom one of the three screws holding the door mirror(there is a bracket going torough the door to support the mirror, at least if your truck has the big mirrors"elephant ears")
3. Door window channel ( if you have old and hard channels they will brake)
4. Screws holding the vent window assembly to the door ( 1 on top of the door frame and 2 on the front part of frame.
5. the bolt holding the down part of the assembly (the metal U-channel where you removed the window channel rubber)

Roll down your window, pull the vent window backwards and down (sometimes they quite hard)
There is not much space to play around with, but it can be taken out without removing the door window. All tough I prefer to remove that one to, since you have the door apart why not clean and lube the window crank,slides and make sure that the rollers on the bottom of the window are moving? Much easier with everything out of the door.
Use white grease if you decide to lube things up.
It´s been a while since I had one out, so I might have forgotten something. Feel free to correct me if Im wrong about something.