My 2002 quad cab (120 K miles) is making an oscillating type noise when I turn fairly tight. wa-wa-wa-wa. I suspect a rear end problem because it seems to me to be some kind of gear noise. Anyone got an idea of what my problem is? Differential? Wheel bearing?

This is not a stearing pump under stress. The turn doesn't need to be that tight. Turning into a parking lot or driveway will cause it.

Thanks,
Chad