Hi DonPaul! We bought our van with factory rear glass but no side glass. I've looked around and the only NV200-specific windows I could find are from C R Laurence: http://www.crlaurence.com/apps/sitesearch/search.aspx?query=nv200
These are "all glass" (frameless) designs, and they are not available with sliders or vents. C R Laurence has other generic, framed windows with sliders or vents but none that would exactly match the cut out area inside the van.
Please post if you find anything that works well!