One problem related to lose power steering has been reported for the 2005 Ford F-350. The most recently reported issues are listed below.
I was driving on a two lane back road around 45 to 50 mph, and my truck started violently shaking and I lost all control of steering. I went into the oncoming lane, luckily no one was coming, and had to hit my brakes hard to get the shaking to stop. It has also happened while driving at speeds of 35-40 on a city street and 60 mph on a highway. This is known as death wobble. The wobble was so bad that it loosened the track bar and the bolt holding the power steering hard line. I lost all power steering fluid within seconds. I have researched it, tried replacing several parts, like tie-rods, and it has lessened a little bit, but if I hit a bumpy road or even just a patch of new pavement, it starts shaking. I have read a lot of other Ford owners are experiencing this same issue with their trucks.