Examine the operator's panel. It is an "L" shaped piece of metal attached to the handlebars. On the upward facing section you will find the discharge chute crank, ignition control switch, and speed control lever. On the front section, which faces the rear of the engine will be the model number. As an example, look for a model designation such as "ST824". Translated, this means your "Sno-Thro" unit has an 8 hp engine, and the width of the impeller opening is 24 inches.
Examine the rear of the clutch housing. It is at the rear of the unit. The engine is mounted above it. Somewhere on the rear facing vertical surface, you will find a small identification plate. On it will be etched the model number and immediately to the right, the serial number of your individual machine.
If you need further guidance or information, log onto the Ariens website at www.ariens.com or contact Ariens' technical support at (920) 756-2141