I have the 2006 in my sig and just reacently I have noticed a shaking in the rear end when i turn the wheels in reverse and ease back slow. it like a popping its hard to explain . it almost feels like the gears in the rear end are not in sink. anyone else have this issue or anything like it.

 

u joint or maybe the slip joint if you have a longbed

 

hopefully its just a crunchy u-joint. feel both u-joints after a long drive and see if one feels warm/hot or look for rust colored dust around the caps. if your worried about rear diff pretty easy to pull cover and see if metal chunks come out w/ fluid then inspect gears. just make sure to brush/clean around gasket real well so you don't get any dirt in.

 

i already replaced the u joint in the rear . I walked around the truck and felt all the wheels and counld slightly feel it in the front wheels too. my abs brake light was coming on and off a few months ago but its not on now. it seems to only happen when foot is on brake going really slow wheels turned in reverse not as much going forward but a little. could it be the abs lockin and unlockin causing it from a faulty abs sensor.