Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 95Get this manual
Powerhead Installation on Lower Unit Install bottom seal (a) and top seal (b) onto drive shaftApply light coat of Quicksilver 2-4-C Multi-Lube onto drive shaft splines
Place new gasket into position on base of powerhead Install powerhead onto drive shaft housing Place slot in shift slide over shift arm pin (c) It may be necessary to rotate propeller shaft to align driveshaft splines with crankshaft splines
ACAUTION
DO NOT use excessive lubricant on top of drive shaft to crankshaft splinesExcess lubricant, that is trapped in clearance space, will not allow drive shaft to fully engage with crankshaftSubsequently, tightening the gear housing nuts (while excess lubricant is on top of drive shaft) will load the drive shaftcrankshaft and damage either or both the powerhead and gear housingTop of drive shaft is to be wiped free of lubricant