I got mine from here
http://www.rsgear.com/products/transmissions/tranzilla.aspx
I have put about 30k on it. I have pulled heavy loads with it and ran it at the track.
Now just need a stronger motor for it.
Mine make a noise on the drivers side front wheel. It does it when I hit bumps and sometimes when it straight. Been doing it since I owned it. I can't find where it is coming from either. I can only hear it when the window is down.