SEI 205-A20 Mercury 2 Stroke 2.07:1 Replacement Lower unitNote 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 2 stroke Mercury engines between 70-125 HP from 1987 to present.Specifications: OE Part#: 45-43031A1; Spline Count: 13; OD of Spline: .873"; Length of Spline: 1.440"; D/S Measurement: 22 3/8"; Gear Ratio: 2.07:1; Gear Teeth Count: 14 - 29; 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 delaye