Ariens Snowblower Auger Gear Set For Older Models withCast Iron Gear Case 12-5/8Genuine Ariens Snowblower Auger Gear set for Older models with cast iron gear cases. This set has the standard # 10183 Helicon Gear for 1 Diameter Shaft. The worm shaft is 12-5/8 long. We have a few Helicon Gears left the are.