02 GU tray back rear diff

[Drankine]

Got a clunking sound in the drive train somewhere. Clunks when changing gears if I let the clutch out to quick. Took it to a mechanic who reckoned it was the gearbox. Anyway, after spending a little over $3000 for him to put a bearing kit through the gearbox and transfer the clunking is still there. The uni's are good so I'm guessing it could only be the rear diff. Can anyone recommend a diff specialist in the Perth area.
Davo