** I have never purchased an after market vent window assy. but have herd some pretty bad reports on them. ** You can rebuild yours if the frames are in good shape a whole lot cheaper than what new ones will cost you. If you purchase the rubber seals from Steele rubber will just about double the price of your rebuild but it would probably be money well spent as Steeles rubber products will last a lot longer than most other after market seals. Your first rebuild will probably take you a couple of hours or more but the second one will be half the time, at least that is the way my rebuild went. It's not really that tuff to rebuild them. Good Luck