There is really poor accountability for these manuals, and most of the time they wind up getting revised and new ones issued. While the info in the older ones are current the old versions are simply forgotten about. I have several manuals, but then again, I don't put them up on Ebay.
Keep in mind, they aren't classified documents, at most they are marked UNCLASSIFIED/FOUO. The rub is that according to the arms control laws, you can't move them across boarders. That was the issue.