I have one of those also. The same blade shape was used on both the 141S and the 491S. Now, who could say with any certainty whether it was the last of the 141 blades being used with new furniture while awaiting the new tang stamp, or an old stock of blades being used to build knives from leftover 49er furniture. The Walden stamped blades predate the release (official) of the 49ers in 1973. Interesting knife!
Michael