1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 239Get this manual
If gear housing is installed on outboard, disconnect (and isolate) spark plug leads from spark plugs before working near the propeller Installing Gear Housing to Drive Shaft Housing
Disconnect (and isolate) spark plug leads before installing gear housing onto drive shaft housing12Position shift lever in NEUTRAL gear positionTilt engine to full "Up" position Engage tilt lock leverShift gear housing into NEUTRALPropeller shaft will rotate freely in either direction1
CAUTION
Do not use automotive grease in the gear housingUse only Quicksilver Gear Lube
Remove any gasket material from "Fill" and "Vent" plugs and gear housingInstall new gaskets on "Fill" and "Vent" plugsIMPORTANT: Never add lubricant without removing "Vent" plugGear housing cannot be filled because of trapped airFill gear housing when driveshaft is in vertical position