I took it to the dealership and they confirmed that I need a new rear differential... At least it's going to get fixed! Thank you.Well, first off, Congrats on the C7 and Welcome to CAC! Not sure how we can really answer your question, as it is a bit vague. A bit more information would be helpful. Is it a new or used, mileage, transmission type, when the whining occurs, where it seems to be coming from. You know, a little more info.