Schrade-Walden, 1947-71, and a picture will help narrow it down even further. The "Schrade Knives Collectors Forum" can be found by clicking on "Forum Categories" at the top of every page and then "Manufacturers Forums" and the Schrade forum is at the very bottom of that list.
The Schrade Knives Collectors Forum has the most specific and accurate information of any forum here. After Schrade closed in 2004 some of the forum members bought all the Shop Floor Records, Minutes of meetings, etc. so this info is not hearsay but factual from the original source.
Post pics of your Schrade-Walden knife there.
kj