SEI Yamaha 2 Stroke V4 Repl Lower Unit 2:1 20"Note for purchasing: You must verify your Gear Ratio. Call for application assistance if needed, and have your engine serial number ready when calling. SE405, 2:1, 20" Driveshaft; Standard Right Hand Rotation; 2 Stroke V4 Yamaha Engines; Includes Sterndrive Engineering's No Fault Warranty for 3 Years; Measuring Guide: Use 20" models when from the top of the driveshaft to the mounting surfaces measures 22"; Use 25" models when from the top of the driveshaft to the mounting surfaces measures 27"; Item is subject to a 20% restocking fee (Boat Covers, Bimini Tops, Outdrives, Drop Ship Items and Special Order Parts)!**Year, Serial Number, and Horsepower are required to order. Please contact us with this information after you place your order otherwise processing will be delayed.