HELP! Had that whirring noise coming from the rear diff area and so changed the coupler bearing on my 2010 AWD Vibe. After $200 CDN for the bearing and $300CDN for labor I still have the same noise. Anyone have some "definitive" advice to offer? Where do I go next? According to the GM fiche there is only 1 bearing but my mechanic said something vague about a 2nd bearing in the coupler? Thanks