I have a 1997 GMC Sierra 4x4, 5.0, 5 spd. When I have both windows rolled down, I can hear a rattle coming in the passenger side window...I don't hear it from the driver's side at all. I checked my brakes to see if anything was loose but it wasn't. Next, I had the front end lubed but the passenger side lower ball joint wouldn't take grease so I thought I had found it. The two top ones were bad too so I had all 4 ball joints replaced, paid the shop $300, and as I drove away I could hear the stupid rattling sound again! Anyone have any ideas? Please!

 

its hard to find some rattles..loose shock?..exhaust?..does it go away when the brake is applied?...missing shims?