It looks like from the markings on the back of the sheath you have a model 13 with a 12 inch blade. Does the sheath have a stone pocket in the front? If so, can you also provide a description or a picture of the front of the sheath and the stone. I'm not the resident expert but this is my best guess and the additional information requested would be helpful to pinpoint the age.

Thanks for sharing,

Dan Snyder
RKS #5537
SHAG #010