I have a quarter window in front of me now and ' your screwed '. Three plastic guides, not really rollers, fixed/stationary two white and one reddish/orange. I have not seen any part of these assemblies repro'ed anywhere. If you can; do as Caspian suggested and work with what you have, maybe rotate to a good spot. Otherwise you will be buying two more quarter windows just for the studs and plastic guides. Drilling the old peened studs off and reinstalling and threading and screwing the new/used ones on. Good luck with this assignment. Brian