81,000 miles on it and starting last week I began to get a vibration at highway speeds. The vibration is both in the seats and the steering wheel, though it feels more so from the front end. HOWEVER, I already have had: both front lower ball joints replaced, the front axle replaced, the tires rotated AND aligned AND balanced, and a missing sway bar link replaced. I have no idea why it still vibrates. My mechanics (yes I tries 2 places) can't get it right. Ideas???