parts finaly turned up from japan today. 5 minuites later, fitted:-
For those that aint seen one before, this is a beatrush (Laile) rear diff brace. I can hear the diff whine a little more now (More so when I roll off the gas down hill).
the anoying thing is although one of the rear bushes on the back of the diff is completely shagged, this bracket didnt cure the slight knock I get, although it has made a big difference.
it's deffinately not the diff, or the shocks. lateral bushes aint great, but theres no play in them or any of the suspension bushes/joints, or the CV joints so diff subframe lock bolts is my next guess.