There was a vent window assembly (the
whole thing, with the front track for the main window going to the bottom of the door) on U-techcenter, but I just looked and can't find it amongst their thousands of items on eBay.... 🤷♂️
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.