SEI Mercury Outboard DFI Alpha Repl Lower Unit 2.31:1 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.The SEI 205 is designed for use with DFI Mercury engines between 70-115 HP from 1987 to present.Specifications:OE Part#: 45-888933A1Spline Count: 13OD of Spline: .873″Length of Spline: 1.635″D/S Measurement: 23″Gear Ratio: 2.31:1, 2.33:1Gear Teeth Count: 13-30/ 12-28Item 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 delay