Vintage Ariens Gravely Snowblower 1 ID Helicon Gear & Worm Shaft with Keyway SAVEThis is a nice old school Ariens cast iron auger gear set. The worm shaft is about 15 5/8 long and has a keyway, not spline. Helicon gear has a 1″ ID (I may also have the older 7/8″ ID gears.