That looks like a correct 1993 USMC M9 Bayonet to me!
Ebay 120322029592
I have one identical to it, mine is in better shpe for the most part but these are interesting as there are a couple varieties. Mine has the full length tang and when the bolt was threaded into the tang it split the tang (hence the reason I think mine was unused). That was certainly not a great idea and the reason there were not many made that way I would guess.
Bill will have more info on these but they are a knife you do not see very often.