I keep records of the ones I see on eBay, in addition to the twenty or so in my collection. Seconds of this pattern are truly a rarity (but don't get your hopes up for the increased value of one, if found). It is much more likely that your stampless knife either had an etch identifier for a special factory order, or was simply ordered stampless by Sears, Pennys, Wards, Belknap, Simmons, etc. A certain percentage of production each year was held back for warranty replacement of both regular production knives and special factory orders. Every so often, this inventory of knives was rotated out into production sales, either as production firsts, or later as seconds. I have several Schrade Old Timer patterns with no tangstamp. None show any evidence of stamp grinding (it takes a deep grind to remove the stamp and it is obvious). They are just a neat oddity, and without the provenance, seldom any way to determine the age. Yours is ground flat on the secondary grind which says pre-1991, and has the "Walden" guard, as I call it, so is relatively early in production. It fits with a knife of the time period you describe.
Codger
PS - An excellent example of an early 165OT by the way! If you get the urge to use it, consider buying a second one already used for that purpose!
