Thanks for the great read! I have been quite interested in these classifications for a number of years, and other than a few previous threads here on Net54, I haven't been able to uncover much.
http://www.net54baseball.com/showthread.php?t=151197
Having said that, what would this thread be without some eye candy

(I couldn't get #2 to upload)
These were all entombed, but I freed them. I still have the flips, and they are all classified as N508's.
Oh, and if anyone knows the location of #5 or #6, I will pay top dollar!!