Thanks for the info, I figured it must be a solenoid.  I once ran a 6 yard loader(I think it was a cat, I don't recall now) and you had to catch your toe behind the accelerator and pull back to shut the fuel off. A lot of the Ford tractors used a manual shutoff to the injector pump until pretty recently and maybe they still do. 
    This oliver 2255 also has fender fuel tanks, but I would guess each is not more than 6 or 8 gallons....sort of small I thought, and they do seem to be factory tanks.