SEI 218 Mercury Outboard 3.0L Repl Lower Unit 1.75 25" Counter RotationNote for purchasing: You must verify your Gear Ratio. Call for application assistance if needed, and have your engine serial number ready when calling. SE218, 1.75:1, 25" Driveshaft; Replaces Most Mercury 3.0L Lower Units - 13 Splines; Counter Rotation; Gear Tooth Count: 12/21; Includes Sterndrive Engineering's No Fault Warranty for 3 Years; The SEI 218 feature dual water pick ups and utilize a metal water pump. SEI units comes with a water tube coupling which is compatible with engine serial numbers 0G438000 and up. When replacing an OEM unit with lower serial number the water tube coupling from the original must be reused. A new one may be purchased using OEM part# 816597A1 or SEI part # 96-116-12K. 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.