Doc,
Depending on make and model, they can be quite rare. But as previous posters have said, not going to be terribly valuable. I have a few production numbers for sunroof cars through 1980, and its hit and miss through the 80s. But if you want a car that no one else has, they are a good choice and make for good conversation. The only draw back is parts if it is not in operating condition, or breaks after you get it. I have a few contacts that might be able to chase down parts, but sometimes it take a great deal of time to get them found. I have set up a website for Mopar Sunroof Cars, but I have not gotten to the later 70s cars yet. But feel free to check it out sometime. Good luck with your search! Scott. www.moparsunroofregistry.com