Trying to track down a vibration that seems to come from the rear end. Driver's side axle shaft has some slight play, maybe a 1/6 of an inch, and I wonder if it isn't enough to cause some vibration and rumble. The shafts of both axles work in and out (from differential to wheel) the same. When I grasp the shaft of the driver's side axle I can turn it ever so slightly back and forth...This play is not evident on the other axle.

Would this be an axle symptom, a differential symptom or even a wheel bearing symptom? Other?

Thanks