As I'm sure you all know there's a wonderfully informative article on the SOG knives web site taken from the Fall 1991 issue of Fighting Knives magazine.
The article as told by Ben Baker (the actual designer of the two original Vietnam war SOG knives we are familiar with as reproductions) recounts the creation and deployment of said knives; specifically the less well known Recon SOG ( my personal fav.) but also the 5th S.F. Bowie knife.
A little direct information as quoted from said article: "When SOG was activated in 1964, it was put under CISO's wing for out-of-country support. The need for nonattributable (sterile) equipment arose, knives and machetes being among the first items sought. The CIA's solution to early demands was to issue European as well as locally made knives, which no one seemed pleased with..."
"... A contract for 1,300 blue-bladed "Knife, indigeous, RECON, 7", w/scabbard & whetstone" at $9.85 each was let to Yogi Shokai. A total of 1,308 knives, including eight bright-bladed protos (CISO-2, SOG-5, CIA-1) were made in Japan."
"In October of 1966, SOG ordered 1,200 sterile knives with six-inch blades and black sheaths at $8.40 per unit. Many were later chromed and engraved for presentation, one of which I proudly own. In March of 1967,an additional lot was ordered,although these were serial numbered 1-3700 for purposes of accountability. Designated "Knife, indigenous, hunting, 6", w/black sheath and whetstone," these possessed no other markings, except for etched numbers on the ricasso (right side.) The word "indigenous" was used to flag sterile items, and innocuous terms used to diffuse local politics. Final delivery was in November of 1967; I believe all the knives were made by the same manufacturer."
"In 1967, the 5th SF requested CISO to assist their Mess Association in the purchase of 1,700 presentation knives etched on the reverse side with the SF crest and wording "5th SPECIAL FORCES GROUP (Abn)" with "VIETNAM" centered underneath. CISO agreed to assist, and deliveries were made by January of 1968, the knives paid for by the 5th's SFMA."
