There's plenty of force to shear off those pins that engage the washer. It happened to my K5. Same setup and only happened on the drivers side.

 

Interesting. I've seen some with broken pins but always assumed it was improper assembly.

So, if the driver's wheel is going counter-clockwise and "forces the rear nut to unscrew" and back up against the locking nut..............but it should already be backed up against the locknut, yes...or rather, it should be backed up against the holed washer which then backs up to the locknut? So in order for anything to move at all the adjusting (rear) nut would have to somehow make the locknut turn, and in order to do that it'd have to find some way around the holed washer which still cannot turn because it's keyed to the spindle? I'm still not seeing how it would loosen?

I can, however, see how the passenger side could tighten and implode the bearings if the pin was broken as it spins CW 99% of the time.

 

The tab that engaged the spindle sheared first, it's just thin metal. It was a bitch to get apart, I had to air chisel it all off.

 

Sean is correct about the tab shearing. It happens on freewheeling (2wd ) hubs too. The best defense is to make sure all is assembled properly and seated well and torqued accurately. The torque stings are not made up. They are based on metallurgical data. The stretch and torsional limits of the parts is well known before they are used. Standard bolts even have torque specs stamped on them. Experienced wrench turners often use a "calibrated touch" meaning they can feel when its about right, but everything has a spec. When you are doing work for a customer and liability is on the line the only way to do it right is with a torque wrench. Then if a part fails you know you were not at fault. The same goes for your own car, especially for the novice. If you follow the specs you know something else was wrong and don't have to question your own work. Harbor Freight or other discount tool stores have cheap torque wrenches that will get the job done. After a while you will developed the "calibrated hand" feel. If your working a lot or for other people get a more accurate one.

 

Ok I'm back from Texas and was looking at the hub and found a metal ring on the inside nearest the outer bearing.... It had some pretty decent sized dents in it... What is this part? I'm going to the parts store tomorrow and really don't wanna make 2 trips....(45 miles one way)... This is my current list:

2 inner bearings
2 outer bearings
2 inner seals

Am I missing something???