Lou,
The solution to your problem has been presented to you. Remove the nipple  
and replace it with the pump from WM that screws in where the nipple was. This  
is the easiest, safest and sure way to solve your problem.
Finding a matching tank online is impossible, at least that's been the  lists 
experience over the past eight years or so. If you do find a tank, it will  
still require the installation of the pump.
 
Rummy