the wheel bearings will loosen up over time, and the way the factory auto hubs use the spindle nuts as part of the engagement of the hub, the play can "grind" the teeth off the hub...rendering it useless.
easiest way to find out is to jack one side up and grab the wheel and see if it moves up and down while a buddy makes sure that it isn't the ball joints movein'
there should be a small amount of "play" but not much......if there is, now would be a good time to get the manual hubs and conversion nuts and have the wheelbearings checked and repacked
l8r, John