Nokta FoRs Gold, a Gold Cube, 2 Keene Sluices and Lord only knows how many pans....not to mention a load of other gear my wife still doesn't know about!
My wild guess it's off some type of equipment with maybe a selector lever to engage it right or left. Possibly some kind of farm or construction equipment that had a hi or low gear selection. Maybe I'll get lucky and find something similar to it in this book I have.