2004 2500 noise under dash

My brother is really getting worried about this noise while he is driving down the road. It sounds as if something is loose in the steering, or somewhere close to that proxitimy. It is a 4X4 extended cab. It does not seem to matter if he is turning or not. He had it check out at a 3rd party garage and they said his supension was fine. No problems there. Any ideas anybody? He says it sound like it is in the dash.

thanks,
Brian

It sounds like the steering shaft clunk noise. there are two options. 1) repack the seals with grease or 2) go to this website http://www.borgeson.com/TruckProductChevy.htm they sell a newly modified steering shaft that eliminates the problem

Thanks for the input. Is it very difficult to get to the shaft to pack the bearings?