Try and Call Champion Trailer at 1-800-229-6690. I don't see it on their web page but they have a lot of trailer supplies. Their techsupport page has a wealth of information on axles/brakes/bearings ....
http://www.championtrailers.com/
Al's Trailer Sales Salem, OR.
http://www.go-rv.com/coast/do/catalo...78&pageNum=627
They can be purchased from any RV dealer or parts store using the Stagparkway catalog
http://www.stagparkway.com/Contact.aspx
I hope this helps some. I'm surprised that shockwarehouse was out of stock.
They seem to be the leading supplier online.
Good Luck
Chris