Hi Tony
After that near lose of a wheel because of the lock or key washer failure we had a lengthy thread on MLU on the topic
Help Need - Front Axle Keeper Washers which listed who had them at that time.
Failure of this keeper is most problematic on the left side of the truck as the normal rotation of the wheel is trying to loosen the left side. Which means I've added removing the nut cover during the spring greasing, brake adjustment scheduled maintenance.
Cheers Phil