With my experience earlier in the year trying to diagnose similar odd noises .. and failing badly .. may I suggest the following as it was the only way I eventually found what was the problem.
Jack the rear of the car up as high as you can and place axle stands really well .. safety being paramount.
Use bottle jacks or similar under the shock absorber lower mounts to raise the wheels to as best as you can the "normal" position .. the idea being to get the wheels "back in line" not "dangling"
You can now run the engine and put the car in gear ... I was surprised that my auto very quickly ran through the gears and settled at just under 30 mph in top.
Providing you are happy with the axle stands .. now get underneath and examine the whole drive train whilst it is rotating .. ( this is why you want the wheels in the "normal" position relative to the diff .. it stops weird noises due to odd angles) ... you can even pull on the handbrake cables to stop each wheel in turn.
In my case this procedure very quickly proved that it was the diff that was making all the wrong noises .. one second hand diff later and all was fixed ..
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HTH ...
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