I had a bad bearing, the spring that centers the shaft inside the bearing was gone/lost do to abuse and neglect. The drive shaft was loose tho. It did not take much to move it around. The colprit was bad bushings in the rear that wore out the rubber housing of center bearing.
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Kevin * HONDA spanking,1985 240DL'Retired' * VOLVO ON!!!!

As everyone else mentioned, It's probably not the Center Bearing. The rubber has springs around it so there is movement.
At 110K you are ready for rear end Bushings. That's about the mileage that they started 'complaining' on me. I also have the manual 5 speed.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me

The bearing is meant to be held tightly by the rubber, but the rubber itself is pretty spongy and allows a surprisingly large amount of play. I replaced one once assuming it was worn out, and found the new one exactly the same.
If your bearing is not gripped properly by the rubber then it may be that the bearing itself is nor running freely. You certainly don't want the outer housing of the bearing spinning round inside the rubber. It would be worth checking that.

But I don't think that can be the cause of your noises. Sounds more like suspension bushes somewhere. IME the 4 torque arm bushes are the likely suspects. If they are less than perfect it lets the front of the axle casing bounce up and down, and hit the stop in the middle of the underfloor.

One time clunk on each acceleration or deceleration could be torque rod or rear trailing arm bushings. A continuous thumping or shuddering could be the drive shaft center support housing, the motor and or transmission mounts. Dan

I wouldn't worry about it. The rubber mount is pretty soft and will allow for some play. As long as it looks to be in good condition and your bearing is complaining (you'd hear it), you're fine.

Is the rubber in sound condition? I think when they are bad, you can see the rubber all torn up and deteriorated. They are supposed to move around a bit, but I'm not sure exactly how much.
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Thanks everyone for all the help, Doug C. 81 242 Brick Off Blocks, turbo bars and wheels, M46; 86 244, B230, 150k , auto; 81 242 Turbo, intercooled, M46, 122k.