This 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 if you need that type instead). Parts are in great condition with no visible wear or damage. If you have any questions, or are not sure if these parts will fit your machine, please ask.