This item has been discontinued by the manufacuter and is no longer available.Sierra 18-2200 Gear SetSierra replacement lower unit gear set for Mercruiser. For 888 s/n 3106717 & up; For #1 units s/n 3469428 & up except MR/Alpha unit (which have no pre-load pin top drive shaft); Interchangeable with: GLM; 11300; Mercruiser Stern Drive; 43-96084A4; 43-61027;