What do I have?

The regular has a gear drive steering, usually open gears, but the last ones had a cover. The later F20 had worm gear steering enclosed in a cast iron case. You can spot the worm gear steering because the shaft goes into the gear case offset from the centerline of the bolster. The regular came with a manifold that exhausted out the bottom, with an elbow arrangement of cast iron. It also had a small brass carburator. The F20 exhaust comes out the top, through the hood, and the carb is larger and cast iron. There are several other differences, but those should start you on the trail. The ID tag was originally on the tool box, under the gas tank. If it is gone, the ID number is also on the frame rail in pretty large characters. F20 will start with F20. Here is a pic of an F20.