Molykote is what if used for my splines for years.
Now for the non servicablility of the bevel box. If you think about how many over the years has had any problems internally the percentage is so low you might as well not do the math. Sure the splines will wear on the drive shaft and spline cup if you do not grease it. And if you drain them and not refill them then your going to have problems. But as a bike owner and your own mechanic how many of you have rebuilt the bevel box? Should everyone have the tools to rebuild something that will probably need rebuilding. And who's going to pay for all these internal parts stock and the tooling. For something Triumph doesn't even build they buy from the Italians. That would be kind of wapsided ! If that type of thought process just would work when your buying components from everywhere just to make one assembly. Anyway is sucks but man is it racist that you can get a black bevel box so much cheaper then the grey one