165-s-120 or 165-r-110, etc.
The first three numbers of the Erie model numbers above are the model. The "s" or the "r" stands for square or rectangular. The last two or three numbers indicate the number of gallons the that would fit in the tank.

Author, 1st & 2nd editions of Gas Pump ID book, 3rd edition is now available at www.gaspumpbible.com
Air Meter ID book also available