You cant go wrong with poly bushing your suspension componants. You will notice a difference for sure, less tyre wear etc. I would polybush the whole arm and do the front bush's also. Bear in mind that the two bolts holding the arm on are NOT re-usable, you need new bolts and you have to tourqe them up and angle tighten them in stages. Its just a case of removing the bottom ball joint and supporting the hub and then removing the bolts for the arms, which are mega tight.