We had a really noisy bevel box. We have a local engineering firm close to us that build gearboxes for motorbike race teams. They had a look at it. They took it apart and superfinished the teeth and put it all back together.
It's still a bit noisy at 40mph but so much better. It is no longer an issue for me. I don't know whether it is the superfinishing of the wheels or the care that has been put into putting it all back together but if you take the box out yourself it was not a costly exercise and well worth the effort.
