This is what little I know about PWA tools. Like WF marked tools other than markings I'm don't think there is a difference between them except possibly the finish in some instances. PWA can span from pre WWII to current production, PWA with 5 digits after it is the most current, 4 digits seems to be sometime post WWII to early 60's/70's, 2-3 digits covers pre to post WWII