Talk to Moser, see if they can make you new ones. Or try to find a local machine shop that has done it a few times before. Certain axles and be machined down, but some taper down smaller after the splines. Those need to be remade.
And heres a simple way to narrow an axle housing.
http://charactersclub.com/simplemachinesforum/index.php?topic=27.0