Picked up this 17, not sure if it would be considered a separate "S" or not, I'm guessing it falls somewhere in the 74-89 era,stone is unmarked, what do you think.
First itineration of the logo "S" stamp.
I am guessing 68-69. Brown Micarta. I think it is stainless even though the S is missing
Brown micarta was done well before 1969, by 4 years or so. Everything else points to a few years earlier than you are thinking, to include the stone. That sheath easily could have been could have been 1966, possibly a bit earlier, as the transition away from harness rivets at the throat was in effect. Good looking knife that knife came with brown, but it had to be the latest one ever!
Being a #17, probably during that time frame of the Viet Nam war, probably not many were being ordered, so brown scale material was probably still floating around as the transition to the "veined green" black micarta had been well underway.
You can check to see if it is unmarked stainless, which would be very uncommon for the period. My guess is not, but take a q-tip and dip it lightly in a bit of cold bluing solution, and dab it on the top of the spine our underneath of the choil. If stainless, it won't take and kind of sits there. If carbon, it will turn immediately. It the latter, a dab of Flitz or some similar product on the other end of the Q-tip will remove the slight discoloration.