Troubleshooting Ford locking hubs for 4 wheel drive

Automatic
hubs can be troublesome. The most common problem is the hub won't
engage. Mud, rust or worn parts inside the hub can prevent the mechanism
from sliding in and locking the hub. The driver may not notice anything
is wrong until he finds himself stuck axle deep in mud and realizes the
front wheels aren't doing anything. Or, he may hear some grinding
noises when he shifts to