1998 Mercury 9.9/15HP 4-stroke outboards factory service manual, Page 285Get this manual
NON BIGFOOT GEAR HOUSING
IMPORTANT: If water tube has been removed, follow installation procedure in Section 5Water tube location is critical for proper alignment to water pump5Tilt outboard to full "UP" position6Place shift handle (tiller models) or shift lever (remote control models) into neutral7Place gear housing into neutral by pushing down on the lower shift shaft (from forward gear) to neutral detent(Propeller will rotate freely in either direction)8Coat splines of drive shaft with 2-4-C wTeflon9Guide gear housing onto drive shaft housing to aligning the following: Keep mating surfaces of gear housingdrive shaft housing parallel