My 2004 XL has begun making a roaring noise similar to, but not the same as a truck with mud tires does. It makes it slightly at all speeds but it is very loud at 35-60 mph, fairly unnoticeable at 60-70, and increases again at 70+. Sometimes, in the mentioned high noise ranges it will stop making any noise briefly. Is this wheel bearings needing to be replaced? The rear end going out?