Hoping some of you can chime in. I have a 2011 qx56 with the 22's and I am getting a low frequency noise from the rear end between 65 and 75 mph. It is definitely a rotational noise and I can't figure it out. I am also becoming annoyed with the thump heard while driving over cracks in the road - sounds like my subwoofers are pumping bass when I hit bumps. I notice the same sound when I am on the highway at 65-75 but it is a constant. I don't think it is a wheel bearing - all are tight. I know the interior is like a resonation chamber since they are built so tight and trying to figure out how to quiet this down. I drive with my windows down most of the time, which masks the sound but now the weather is turning and I will be unable to do that in the winter.

I put a machinist's dial on the driveshaft and the rotational difference is .002 so it is not a bad driveshaft. U joints are also tight.

Here are my thoughts:

- rubber shock mounts
- differential mounts
- bad shocks?

This would be tough to diagnose over the internet.
I'd try some of the more simple stuff first. Can you rotate your tires and see if the noise changes? Does the noise change if you're on the throttle (under load), neutral throttle (maybe only slightly decelerating), or off the throttle (engine braking)?