Vega Tool Base
Ken,
I went throught the same search when i was trying to fit a base under my 3520, the only one i found was the Vega Machine Mover system. It comes in three sizes so measure the legs of your lathe and call Packard, they can order one for you. The Vega website has a description if you want to research it.
I have one under my 3520 and really like it, it is the only mobile base that i have found that actully sits on the floor while not actually being rolled around.
If you have any questions send me an email.
Dave