I need your expertise, I have a 91 suburban 3/4 ton with the 14 SF rear end lifted with 33's. It is only used as a toy hauler/camping vehicle. When backing up out of a driveway, the axles move in and out, creating a knocking noise. You can grab the tire and move it in and out. My question is, how much play in the axles is acceptable? The C clips seem to be in place, no excessive metal in the cover or magnet. The Gov. lock works fine with no unusal noises. Am I to picky, or is this a usual symtom when larger than stock tires are added?