If I listen carefully, I can hear a whining sound coming from the rear end when accelerating. I don't notice the sound when cruising however. I recently replaced the differential oil with Mobil 1 diff oil and haven't noticed any leaking. The rubber boots around my CV joints are cracked but don't seem to leak either.

Any suggestions or advice is as always greatly appreciated.

On my club mate's 124, I rode in his car to troubleshoot a "whining" sound from his rear.

The "whining" seemed to follow the speed of the car and at very low speeds, was unnoticeable.

At higher speeds, VERY loud.

Checked the rear wheel bearings and found the left rear one shot.Swapped out both and "whining" is history!

This whining is subtle, I don't hear it at speed.