From what I can tell it is just a bar and bolt, it doesn't look like it's attached to a bigger piece. It presses on the window near the lock to keep the right tension so the window doesn't flop around. My driver-side window pops out at the top and doesn't roll up properly.Is it the window stop?
Up for sale is a drivers side OEM door window guide U bracket. This is basically the bar that guides the door glass up and down inside the door itself and usually has a small weatherstrip inside of it.www.ebay.com