i had the same thing with mine ... before i put mylift on come to find out .... after i installed my lift i got to looking it was one of two things casueing it ...i had bad shock bushings plus i had a bad transfer mount casueing it to rock and tap against the tail pipe from time to time casueing a tapping sound ???? take your pick lol
All jacked up on Mt Dew, And commin at you like a Spider Monkey !!!!