86 gt vert. When driving in 2nd gear lets say thru a parking lot, when i let off the gas i hear a loud pop sound coming from the passenger side rear. It sounds like someone threw a big ball bearing at the side of the car. Accelerate then let off again same thing. Thought maybe the u-joints were bad, but when checking they seem tight. While turning driveshaft back and forth there is play in the rearend. I can turn maybe an 1/8" either way without the tires moving. I get the same thing if i spin the tire back and forth. There is no whining or grinding noise, and the sound appears to be only on the one side. The rearend is stock and original with 2.73 gears, 373,000 + miles,and has never had any service other than oil change and friction modifier every 50,000 miles. It drives good and seems to hookup properly. It never makes the sound when starting off from a stop, or any accelerating. Any suggestions?