Some vehicles had very loud bevel boxes, like the one above, where you could easily hear it over everything else. Some of us got lucky and have realitvley silent bevel boxes. Morgan released the bevel box isolation kit for the noisy units, which helps somewhat, coupled with a thorough flushing of fluid and filled with the proper redline fluid was the easiest fix for the loud units.
Further to this, it's been found that the upgraded bevel box mounting (the NVH kit) doesn't really help and is a very heavy bit of kit for no real gain. If you get a car without it I would recommend that you don't bother to get it retrofitted.
As Charlie says, different oil does help, Redline and Millers EP140 seem to be the best so far and it's fairly easy to change and try different types.
To put the noise into context, it typically occurs in a fairly small speed range of around 5-10 mph somewhere between 45-65 mph.
