Originally Posted by jgalloner

There are no noticeable vibrations, and the sound only happens when brakes are applied.

The dealership had a Regional Technician Specialist come up to look at the problem. They swapped rear rotors and wheels from another 370z, replaced rear axle shafts, rear differential, upper control arm. Sound didn't go away. After all this, they concluded that this is a characteristic of the model/year.