Was up in the mountains today and my friend noticed (when outside of truck) that my 3rd and axle flex really hard when I let out the clutch. I have also have noticed sometimes in the mornings when it is cold the rear end hops for just a moment until it gets warmed up. I would assume that my U-joint has taken a dump on me? Is this correct? I have never seen anyones flex to that amount, but then again thats not something you notice all the time I guess.