Safely Jack the whole car off of the ground; or do what ever you need to do so the Rear Wheels are off of the Ground and there is enough room for you to get under the Car and use a Mechanics Stethoscope (or substitute) to listen to the Drive Shaft Support Bearing while the Engine is running and the Car is in Gear. (Also listen to the Pinion Gear and the rest of the Differential and the Tail end of the Transmission while you are doing the above.)

When I did this on my Volvo the Drive shaft Support Gearing was actual bobbing up and down and it sounded gritty. Sure enough it was no good.

If you remove the Drive shaft Support from the Drive Shaft you have a good chance of feeling that the Bearing is rough

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84 300D, 82 Volvo 244Gl Diesel