Despite the change of diff and the offside CV joints, the clunky noise is still there. It only appears when not on or off load, somewhere in between. The centre bearing has a little movement in it but, as the support around it is made of rubber, this is to be expected.

Centre bearing replacement is not that arduous, even if it means removing the propshaft (ha ha, famous last words!)

I will get a second opinion and see where we can go next.