CornDude: Just measure your trailer and current axle, and go to your local trailer parts house. There are only a few axle manufacturers, and the trailer companies buy from them. Dexter is one brand that comes to mind.
I just went to Google local (very useful site BTW) and found your town, and then searched for trailer parts, and several came up in Peoria, but the one in Normal I'm most familiar with, and would suggest.
Redneck Trailer Supplies
109 Merle LN, Normal, IL
(309) 862-1000
Finally, torsion axles are nice, but demanding. They don't self-level like springs, so you have to make sure your trailer is level on the ball, which you should do anyway.