I was driving on the road in town when my rear locker well locked! All of a sudden I could not make a turn without scrubbing the inside tire! It did not matter which side was inside left or right. I stopped the truck for a few minutes and when I moved it again the diff was unlocked and worked fine. On the '99 locker, what causes it to lock? I thought it only did that in 4-Lo... Anybody have an idea as to why this happened and how to prevent it from happening again?