All About Pocket Knives

i found this in a pile of old cloths, it's shaped more like a Buck. WESTERN U.S.A. 51 stainless with an M lower down. Nickle bolsters and wood panels, 3 pins. Only 51's i see are all metal, any idea on year?

The "M" is the date code. "A" = 1977, "B" = 1978,..... "M" = 1989.

Thanks! I had a couple 532's both bigger handled or wider and couldn't find a wood and nickle 51.

Cleaned the edge up a lot but still needs more, need to polish the bolsters . These are great little knives I never knew about.