Weird Lose Noise Coming From Rear Seats R33

[KnightRiderR33]

Hey guys i have an r33 gtst s1 and there seems to be a noise like something is lose ive checked the area roughly and didnt find anything they seemed lose but just incase i put some foam padding under the parcel tray. My next thought that it could be my shocks i have tien D150 coils all round and ill be honest they are stiff as shit. Ive been told that when they go to stiff the shocks are gone but others told me that it could be the stiffness rate is to stiff for australian roads but on that matter could it be some sort of bush thats worn out i only hear it from the pasgener rear side. Sometimes the noise is a little rattle but when i hit a bump it sounds like its bouncing off a surface then hitting down hard. Any thoughts?

[redlined_az]

Mine had similar noise fixed it by replacing the strut.