hi iv just replaced every bush and arm on the rear its not a big job really all tolls can be hired for removing bushes arms just bolt on easy and cheap really, a quick and easy way to check what needs replacing is to release the pressure out of the rear air bags make sure you remove the fuse for the compressor then jack the rear up and get under it and get someone to shaxk the wheels and you will see play feel round till you find worm parts, releasing the air from air bags is essential as it releaves pressure of conponants, do a search on youtube and you will find easy steps