It has been on eBay for a LONG time.... I had not seen it recently.
That particular seller always has a lot of interesting stuff.
I have one exactly like it, .... like DM says, it is all correct.
Some one jump me if I am wrong but I think barrel nuts are pretty specific to the first 2-3 years or so of factory production. Of the few pre factory knives I have in my collection, some are pinned but most seem to have threaded pommels. The barrel nut simplifies indexing the pommel correctly on a threaded tang. Of course, pinning eliminates that problem completely.