That design of hub went obsolete a LONG time ago. I'd be surprised to find that anyone makes a compatible lockout to work with it. Back when NAPCO was making 4WD trucks, they weren't toys. They worked for a living, mostly off road all the time, and a disconnector hub just wasn't needed.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!