[panhead george]

I have a 2002 f350 supecab dually 2wd. After replacing brakes, I crawled underneath to look at the driveshaft and rear end to check the u-joints. I have a 2 piece shaft. Behind the yoke to the rear of the intermediate bearing for the shaft, there is a rubber sleeve around the shaft. What is this covering? It has stainles ties holding it on.. not hose clamps. There seems to be some play at this joint.

 

[fordsforever73]

That would be a dust boot around the slip joint. The slip joint allows the drive shaft to change length as the suspension moves around. They should be periodically greased but get neglected by most due to the amount of work involved.