fuel selector valve

I am looking for a Fuel Tank selector valve..I have tried to no avail to find one on the net. It is the small white (T and H Marine) plastic peice that allows you to switch tanks from one side to the other on the side of the boat. It has a cable that attaches it to the dial. It has three barbs that connects the line out of both tanks, into the filter, then into the bulb and finally into the motor...anyone know where I can get one? Or if it would hurt to merely put a plastic tee valve in its place. thanks all for your help..