Never go four wheeling with only one vehicle.
That's the RULE.
I broke that rule.
Once.
I paid for it.
In September of 2003 my parents came to visit me and I took them out in the desert. We were driving along on a road that required 4-Wheel-Low. All of a sudden, I heard CLANK, CLANK, CLANK!
The U-Joint that connects my front drive shaft to the front differential had disconnected. A bolt that held one of the two C-Clamps that held the U-Joint together had worked itself out and the C-Clamp came loose.
Fortunately, just as I was getting ready to clamp the drive shaft to the frame of the Jeep, a mechanic happened along and helped me perform said task.
Then, we were able to limp out of there in 2-Wheel-High.