Success. The mechanic fitted all 3 rear knuckle bush's and the car is quiet again. feels like new. Cant say if it was any particular as all replaced same time. If it had worked out as planned (as in i had bought the correct parts originally) I wouldn't have replaced the trailing arm/chassis bush, but I do think this helped also.. as a note, I had 3 different mechanics check for play in this area and none found anything, in the end it was me asking for these parts to be replaced to to see if it fixed the noise.. the febi website has everything I needed..