@slestak, if you are looking for a universal replacement axle, then I would advise using a flexproof, as they are only a few bucks more than the standard axles, below is the one I am going to use.
http://www.mfgsupply.com/gomini/gomi...az1413-40.html
If replacing the stock axle, then I would also advise you to add at least 1 more axle bearing in the center of the swingarm for support, some have added up to 3 or 4, but I think it might be overkill for a flexproof axle.
As far as a direct replacement, I heard mixed reviews on the HD replacement axles, some break, some bend, heck, some even were bent right out of the box.
@x-bird, I read your post about shaving down the #50 sprockets to the 520 size, but I was hoping someone out there made some 520's, or at least I could find a 530 output shaft sprocket for the engine, then just use 530 chain and sprockets for the rest, but can not seem to find either one.