I have had the noise since they dropped the whole rear end to fix the diff leak. Sounds like the rear parcel shelf area however it is definitely suspension related. My car has been in about 10 times for this problem. Total days off the road have been close to 20. You would not believe the work they have done to the car to eliminate the noise. We even got to the stage where there were welds to the rear parcel shelf, to welds in the body seams. They thought the body was flexing. Then we got to the stage of taking parts out of the rear of the car on each visit to isolate the problem ie boot trim, spare tyre, trim under the parcel shelf and so on. Each time the noise was still there. Finally they looked at the suspension. It appears that they didn't put the thing back together in the first place. They said they dropped the rear end again and put it back together. Car was going great for 2 weeks, however after driving from Sydney to Brisbane and back over the weekend and then to work today it is starting to rear its ugly head again. Might have a chat to the Service boys again tomorrow, they haven't heard or seen me for 2 weeks now.