Dispatch suspension noise

[RPWC]

My Dispatch has been for a while now,making a clonking/creaking noise. It is coming from the n/s/r, and only occurs when turning right.
I have checked the spring,shocker,anti roll bar bushes and swinging arm,and cannot find anything amiss .I have also had someone jumping up and down on the back of the van while I checked underneath,again couldn't find anything wrong, it only occurs when turning right and van is moving.
Can anyone enlighten me please?

[RPWC]

Anyone??