As much as I dislike posting links to help with a problem, some times it's easier to actually see what to do rather than build a word picture for you... hence, take a look to see if this helps:
this turned out to be a joke was told noise was from back axle eek
went to a different garage that sells old rac vans woul you belive it
turnedout to be centre bearing on propshaft got it done for £102 inc vat phew