A 1996 Ford F350 4x4 pickup arrived today for its regular maintenance service and a 4x4 inop concern. In order to verify the concern, I hit the gravel part of our parking lot and pulled the transfer case lever into 4-High to find no engagement of the front drive wheels. This truck has automatic locking front hubs, (as opposed to the manual hubs where a knob must be turned at each front wheel hub to "lock" the front axles). I brought it inside and started taking stuff apart.

The photos above and below are of the cam in the right front locking hub assembly. The square key seen in the photos aligns with a keyway on the axle shaft. This key is in good shape.

The keyway where the above key fits on the right front wheel hub was also in good shape.

This keyway was in good shape.

No obvious damage here.

The cam for the left front wheel hub was a different story.

Whereas the right side cam was square, the key of the left side cam was damaged.

The damage to the key of the left side cam was more visible with the cam on my bench.

At some point, the key began to slip and rotate within the hub.

The key was damaged to the point where it wouldn't engage the keyway.

Damaged key on the left side cam.

As expected, the keyway on the spindle was also damaged.

Damaged left front spindle keyway.

Damaged left front spindle keyway.

With the cam key ground down to nothing, the entire cam began to spin on the spindle and damaged it as well.

In the end, the customer decided to forgo the automatic hubs and convert the truck to manual hubs, which was accomplished via a conversion kit.