Re: [MBZ] 1979 240D, Noise in back end

[Peter Frederick]

Check the differential mount, rear subframe mounts. and the flex disks. 
 Diffs usually don't make growling noises when they go bad, but a bad 
mount or flex disk could be transmitting vibration, or causing 
driveline noise.

I would also try it out of gear -- if the noise goes away, it's most 
likely driveline related.

Peter