my 01' 4x4 makes a loud noise when crossing railroad tracks, etc. sounds like something is loose! I have bilstein shocks, moog track bar, dss and the ball joints are ok. truck steers good, no death wobble! it only makes the noise on a pretty good bump like railroad tracks or a good sized pothole, recently had it aligned and they didn't note anything loose, any ideas on where and how to check other possibilities?