Nice Gerber!! But they were never U.S. military issue knives. They were private purchase knives available at the PX stores, from catalogs, and directly from Gerber, and very popular in 'Nam. Voodoo, your knife is a second model F-S knife, and a nice find, especially for the price!! It is mid-war vintage. Sadly the tip has been broken and re-shaped, hard to get a real idea of overall condition from your pics. Still probably worth a couple hundred U.S. dollars. Nice ones with original sheaths bring around $500-600. Mint ones in mint sheaths a little more.