Unfortunately I cannot take credit for installing the window in my van, it was already there when I bought it, but I can give you some photos of it installed, and walk you through adding the opening mechanisms.
here was the van as I bought it, with a metal bar holding the windows shut.
This worked for me, it was nice to be able to see out that window when merging or changing lanes. I am sure that I would have crashed into someone without it. But with summer approaching it has become time to open it up.
I spent some time scouring the yards and found two different styles of window opening mechanisms, from two different eras. Initially I just brought home the newer style, but they would not work on my cargo van. The "seat" where the base rests was not large enough to use them. So I went back out and found the older two screw style and they work.
The hole for the window is the same size as you would find in a window van. So if you are going to install a window like this, go to a junkyard and remove one. That will be the best way to learn how they go in. Then make a cardboard cutout of the opening and get some reference measurements from the existing van on how to center the hole for the cut.
You will need the window, the exterior seal and track that the seal is inside, the mounting bolts and nuts that go through the body, and then these window mechanisms with some screws to attach them.
The difference that I see with my van and probably all vans that didn't originally come with a window is that the metal is not stamped in to make the window mount flush with the body. This presents two differences from a stock window. It will stick out a little, and you will need to use some sort of filler between the interior and exterior skins of the van. In my van they used a piece of window seal in between the two pieces of metal and then covered it with a strip of black duct tape before they installed the exterior window trim/seal and window.
you will also note from the picture that the bolts and nuts holding the window frame and seal in are longer than the ones that you will take out of the junkyard van. You will need to take the stock ones to a fastener store and find a suitable longer replacement.