It is a problem with the nut backing off. There is a fix for it. I can't remember b/c it hasn't been brought up in a while. Someone will be able to help you. And you can do the fix yourself instead of having a shop do it.
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2001 extra cab 2500 SLT laramie (dark blue over silver) 4x4 S.O. 55 block, 47re, silencer ring/resonator/muffler are MIA, gauges, big bumper up front, B&W turnover ball, 315 buck shots, and Quadzilla XZT+ (thanks DieselNut)
'89 GMC Sierra SLX 1500 4x4 186K 350TBI w/custom 400 tranny
'06 Freightliner Business Class M2 106 tandem w/lockers,30k# winch, and Altec digger/derrick