Well, just got back from the dealer. Took two hours to figure out what mine was coming from. At first, we thought strut housing or maybe the strut itself. But that was not it.
My rear bumper is dented, like alot of 4runners. It seems the bottom of my rear bumper is smacking the top of my trailer hitch. We just bent that little section of my rear bumper up a few millimeters and....POOF...cclanking noise is all gone.