Mystery model B engine

[2manycars]

My brother bought a model B engine with a strange number stamping. The number is stamped on the flywheel housing, as B engines are, but the number is odd. This engine also has a raised boss on the left side, where the model A engine has the serial number stamped, but the boss is about 2 inches by 3 inches, and it is thick, and has two tapped holes in it. We are wondering if this was some industrial application.