[Brent]

It didn't appear that it had moved in its mounting. There was no sign of any physical trauma to the axle or slave area. Upon removing the slave, the finger that slides the sleeve appeared to have a slight bend away from the diff. So the light on the dash was showing (correctly) that the slave had moved far enough to engage the lock. The slave has slotted mounting holes that allow for an adjustment. So, I engaged the lock collar with a screw driver, engaged the locker on the dash, and re-assembled it in the locked position. We then simply tested it to make sure it engaged and released a couple of times (on jack stands).

To avoid any injury to my pride we took it out and ran the trail (Hells Revenge) that the truck had to sit out earlier in the day. It took us about 90 minutes to run the trail solo. The truck never missed a beat and ran Cliffhanger the next day without a problem as well.

I am going to pull the front one as well to try and determine if in fact the slave pin is bent, or if the possibility of it being knocked out of adjustment is the more likely cause.

I'm not entirely sure WHY it happened, I sure am pleased though, that it was a simple and free repair.