Clunking sound when in reverse

[jackfor]

I bought a brand new right axel and installed it, the clunking sound was a little less presen but still there. Also replace the engine mount, nothing changed. I checked under the car with a friend during almost an hour, we did not find anything abnormal. Anyone has that problem? The infamous clunking sound is more present when in reverse and it sound like metal on metal. Any help would be appreciated.