I seem to have a lot of play in my rear-end (boy, that really sounds like fun!)

I get a bump when letting of the throttle on the highway. I thought it may be the U-joints, but found I can turn the driveshaft with my hand to about 1 or 2 o'clock with the brakes on. Is this much play normal? Is there an adjustment or tension setting in the differential? Or, does this mean I need new gears?

Any suggestions?