Wired sqweeking noise
 

I have a 2000 chevy blazer LS. It only has 80000 miles on it. When ever I drive the sqweeking noise begins. It gets fast and faster the faster I go. When I slow down it slows down. I thought it was a wheel bearing. But it's not coming from any of the wheels. I have tested it. When it park or nutral and give it gas there is no noise when I put it in drive or reverse and move I hear it. Could it be a bad u joint?

That is my first guess, U-joint