I found these all boxed up while cleaning up at fab32's barn. There's only one identifying mark on the bottom. First letter is an S but I have no clue what the next one is?
Look familiar? SP103 You can learn more at this thread... http://www.jalopyjournal.com/forum/threads/sp-tops-how-were-they-handled.542342/ In short it appears they are repops which doesn't surprise me as I don't think the originals had any markings on them. Well, that and the lack of SP logo of course... Even repops are going for $60-$80 unpolished and $250-$300 polished. Yes, $300, surprised me too.