Quote Originally Posted by rdobbs View Post
I can take my hands and shake both back tires and I feel some
slack. Don't have this in front. Was wondering if I could have
something possibly loose or maybe bad bearings.
What do you mean by "...take my hands and shake both back tires..."? Is the "slack" in & out, pushing & pulling away from the differential or do you mean pulling left, pushing right and reversing that motion? Pro70z28's idea of a borrowing a set of tires from another truck is a good one, and cannot be argued by the tire store if the "bump" comes back with the new tires. Another thought is to put a dial indicator on them, check the runout of the tires, the edge of the rims, and then the axles/rotors. How about your u-joints? They sometimes shake at a harmonic until they get really bad.