I've recently put my new engine in my erst and replaced the clutch with an AP paddle one. Since then I've had a wyning noise from the engine on downshifting. I thought at first it might of benn the alternator, but it turns out it's the diff bearings that are shagged. I'm going to replace them and was wondering how easy is it? do I have to get one or two bearings? has anyonew done this before?