You might check with a W. W. Grainger store or go to their online site. They may have what you're looking for.
But, let me clarify something...this is an exhaust fan ventilator that mounts on the exterior wall and is vented to the bath? Sounds like something on a smaller scale of a warehouse wall vent?
[This message has been edited by Indcom (edited 03-07-2005).]