I don't specialize in the Schrade folders, and actually have none of the folding hunters in my collection (donations welcomed), so I can't answer this one conclusively. The 127UH Folding Hunter was cataloged from 1968-69, absent from 1970-71, reappeared 1972-1988 according to Mr. Clemente. He says that there was a hole in the bolster in 1968-69, none in 1974-75, added back in 1976-88. This information, as I recall, is based upon factory catalog compilations. Sometimes the catalogs were wrong, sometimes illustrations were carried over for years after engineering change orders were implemented.
The use of "SCHRADE+" indicates a knife made after circa 1974, so that is your best real clue. The 1968-69, 1972-early 1973 knives would have a SCHRADE-WALDEN tangstamp. And Tim Faust indicated here that it was around 1974 that they first used the "+" mark to indicate stainless.
Codger
