Just for info's sake-This is a link to cheap hubs for the Azusa axles:
http://www.mfgsupply.com/53-681.html
You'd use the snap ring type axle-
Correct me if I'm wrong ckau- his wheel hub adaptor is keyed not splined
The pic's is a spare wheel hub for the "different type of buggy" & universal disk brake/sprocket holder made from billet aluminum and are exceptionally strong. The sprocket holder comes with multiple key ways, if one get's loose you can just rotate it.