Rich is correct about the dial - its a meter or counter for tracking fuel delivery one 5 gallon bucket at a time. A truck like that would have been used for farm, home and small business delivery: 2 grades of gas, diesel, kerosene and/or home heating oil. Notice the faucets at the rear behind a relatively weak bumper and no overturn guards or rails on top: definitely pre-DOT.
It is cool!!
Also notice it looks like 4 individual tanks banded together. A friend of mine whose an old guy in the truck tank business thinks its a Morrison Brothers built in Dubuque, Iowa. They are over 150 years old and still in business, but they no longer build truck tanks. Have fun with it KC.
