That is a well worn pattern number 8313 "carpenter's whittler" as Boker called it.
That is a neat old knife as it is a true whittler with split backsprings and a tapered brass liner between.
Whipping open my copy of BOKER: TWO CENTURIES AND TWO COUNTRIES REPRESENTING ONE NAME IN CUTLERY EXCELLENCE, written by a couple of really good looking and quite intelligent young men...
On page 175, I can estimate that Boker USA made this pattern with delrin handles from the early 1970s to 1981.
Too bad the tree is worn off the shield, or you would be able to tell if it was made before 1976 or after.
I hope this helps,