I'm sure its uses a 5/8 axle.
Its more than likely from V-Twin Cycle (same as Tedds Cycle) in New York..
I've sold many of them before and never had a problem with them..
Can't say that I've ever used one though.. I'd never use a mini drum on a bike of mine.
You might try Red and Kate at Cycle One.. I believe they're a V-Twin dealer and should be able to help you out.
If you plan on using it on a stock fork.. Red can help you with adapting the size as well
Thats whats handy about them  They'/re willing to not only get you the parts.. but do whats necessary to make it work..
http://www.cycleonemanufacturing.com/

Build it the way you want it ..... then learn how to ride it like you own it..
www.lowridersbysummers.com