Clutch? You'd recognize slippage by watching the tach. My slippy clutches were not particularly noisy.

You're not gonna get a CVT now are you? haha


What else could cause this?
CV joint
wheel bearing (noise wouldn't change with engine RPM) (actually, none of these examples would)
output shaft bearing

Nothing lasts forever. If you had to replace anything I'd say you got your money's worth.