I have 2005 GMC Sierra 1500 4x4 crew and had the steering column "intermidiate shaft" replaced last year which gave a loud knock. Guess the GMC/Chevys are notorious for that problem.

What I have now is a small click/knock under the drivers position that mystifies me. I don't feel it in the steering wheel...yet it don't always happen when I hit a seam in the road or a bump. It's at the slower <25mph that is most noticeable. At highway speeds it not there.

Realistically from here here is no way to diagnose road noises. There were issues with the upper ft shock mount bushing making noises.

maxwedge (http://www.automotiveforums.com/vbulletin/member.php?u=19971), yea, understand. examples of the shock mount bushing is a good starting point.

It can't hurt.

Lefty