Bill,
From my perspective, the thong hole diameter is a little too large which may be a tell that the liner was drilled out.
Jack: Can you comment re the stamp and associated timeframe?
Here's another that just popped up. Not a SF claim, but an 80's knife being touted as VN era. The spacer set alone is enough to call foul.
http://www.ebay.com/itm/Vintage-VIET...0AAOSwhQhY66rl
Thanks,
Ron