Many times patent dates are of no help, what you need is the Model number for the tank.
First of all a picture is necessary if you do not have the model number. Your tank is probably pictured in my Gas Pump ID book (out of print), but Wayne made many all a little bit different.
I would suggest you go to this page of my website: http://petrolianacollectibles.com/wayne%20pumps.htm
then start clicking on the very low numbers on the left side. Your tank probably has a model number of below 100.
Just saw the post above this one, again to that webpage and click on the 228.