I think it started life as a trapper. Looks like celluloid covers and I'd say they have started to outgas (release nitric acid vapors). I would recommend not storing this knife with other knives or metal items. The nitric acid will attack them.
KaBar has a forum here. The factory rep is usually pretty good about helping people date old KaBar products. I'm willing to leave this thread here, but if you want it moved, either PM Gary or me, or you can use the "Report Post" button at the bottom left of your opening post and ask to have the thread moved.