Because working now nearly 2 year on the Bevel-box, maybe this is the answer.
We have found that they all were M40 1.5 with a collar, key 55mm
As far as we know only Quaife has the exactly right ones, with the collar inside the nut.
We use in our project M40 x 1.5 with a colour which extends. The ones we use and have for sale are Key 50mm
Most M3W do not have a dustcover on the swing-arm at that side.
It is better to make an inside dustcover to protect the left bearing of the swing arm.
BTW Our Bevel box project has done now several bench and drive test and the results have even flabbergasted us.
No noise, no vibration. For the first time I hear a little 'swoesj' of my chain-drive ;-0
