Bad pitman arm
 

If you wouldn't ind here is my post on CF. http://www.cumminsforum.com/forum/3r...rm-issues.html

It is most likely the sector shaft in the steering box which the pitman arm attaches too. Grab the steering column shaft from under the truck and gently wiggle it back and forth, pay close attention to the splined shaft the enters the steering box. Any side to side play in that shaft is no good and the most likely cause of the noise. Also look for rust around the area where the sector shaft enters the steering box.

I have had 2 steering box's replaced under warranty on my 06 because of this.

I bet you are right. What a POS design. If I have to do a new box i'll do a brace as well. Lame throwing money at somthing that should not be going bad at this milage.