CT808

Hi Not sure if anyone has had this problem before. I have an R-Reg Galaxy 2.9 4x4 Auto. its only done 53K miles but it has started to make a knocking noise The noise only starts after the car has been driven for ~20 miles, then it always there. It sounds and feels very clunky, almost like worn engine mounts on acceleration / deceleration It does it whether the car is in gear or neutral whilst moving, and tends to be more pronounced when cornering. However if you stop the car and leave it for a couple of hours it goes away. It is truly baffling. I am not sure whether this likely to Driveshafts or Auto box or 4x4 diff or maybe something completely different, so any feedback would be greatly appreciated. Thanks Carl