John:
In the book, as shown on the first graphic in an earlier post in this thread, Platts states:
"During the 1960's, tang stamps on both sheath knives and pocket knives were gradually changed to "Western USA" - except for the number 381, which was marked Western, Boulder, Colorado, Made in USA well into the 1970's."
I would imagine your 62 falls into that category of "gradually changed in the 1960's". Platts further states on that page, "this information about tang stamps and blade etches should be taken as a general rule". This is about as close as I could come. Hopefully a Western collector with more knowledge may be able to provide more infomation.
Is your 62 bone stag or delrin? That might be a clue as well, although not one for pin pointing a date.