My 1996 2500, 4x4 has about 245K on the engine. My steering wheel can be turned a good couple of inches without any movement in the wheels - what might be the cause of this problem? When I take my foot off the pedal, say at about 80kmhr, I feel a thunk in my steering wheel - what might cause this?

 

A new steering box will take care of most of your play, maybe some tie rod ends as well, I'm not sure about the clunk, maybe motor mounts?

 

pitman arm/drag link is a common problem too