Well, I finally took my car into the dealership to get the rearend whine checked out and I even had the service manager ride with me and he totally agreed that it was the diff. When the tech test drove it, he drove it with the service manager and said that it was road noise. Well, when they told me this, I was pretty steamed 'cause I was not about to fall for that BS! So the next day the service manager rode with me again and on different surfaces in which the noise did not change, thus proving that it was not the tires. He mentioned that the tech didn't even get it up past 48 mph (which is where the whine starts), so the tech obviously never heard it. So the service manager, once again convinced that it was the rearend whining, said he was going to drive this time and show the technician what he heard. I guess I will see Monday if I will be getting a replacement rearend. The service manager also said that he had never heard of the rearends on these cars going out.