I redid a '67 Satellite a few years ago and my buddy has a couple of '66 Belvederes so I've looked pretty hard for parts i.e. rear tail light bezels and lenses, headlight trim rings, body mouldings, etc.. As far as I know no one makes repro quarters yet (or ever). If you find NOS quarters they will be BIG money (thats a big if). You might find a rust free shell. To me this is a serious factor when considering the '66/67 Belvedere/Satellite/GTX cars for restoration. I've bought some of the patch panels but they are junk. Even the trunk extensions needed modification to fit. I think finding a sheet metal crafter who can make proper patch panels is the best bet. Getting the profile around the rear wheel lip isn't easy but some of these rod guys are pretty good.