I just went through changing some windows. My van is a 2005 Chevy Astro. It has pop-out windows that hinged at the top on two for the four rear rectangular windows. The other two are permanently glued in. On the rear barn doors, I had permanently glued in windows, but noticed that some of the older Astros, with the exact same doors, came with the hinged, pop-out windows. Of course, sliding windows with screen would have been ideal, but those never came from the factory. So I found the rear pop-open windows (had to try a few junkyards to get all the parts). It was hard finding a place to install them. Glass shops suggested a body shop, and body shops suggested a glass shop. They all just want to replace what was there originally, and not drill any new holes. But I finally found a body shop to remove my glued-in windows and install the pop-out windows for $150.<br><br>If you have a van with glued in windows, but pop-open windows were available as an option, you can do what I did. But if you want sliding windows, that could be harder. I know some older Toyota Land Cruisers could get sliding windows, but only from Australia. They fit right in, but it was expensive because you had to find someone selling them in Australia and have them shipped.<br><br>But, I know most conversion vans started life as a cargo van. Then they got aftermarket windows, much like the one in the first post of this thread. I think most of those had a small lower portion with a sliding window and screen. I'm thinking you could find out the manufacturer and see if they still sell the same size windows, but in a version that opens. If not, look for a different brand the same size or a bit larger and have them enlarge with the window opening to accomodate the new window. <br><br>Below is a picture of my van with the newly installed pop-out rear barn door windows. I will attach screens with velcro or magnets, from the inside. If you're not as concerned about stealth, you could more easily attach screens on the outside with magnets.