1985 Mercury Outboard V-300 V-3.4L Shop Service Manual, Page 222Get this manual
Adaptor Replacement (continued)
Remove" ring (e), coupling (fl, and studs from old adaptor and install them in new adaptor as shown Align coupling slot (shall ow) wit adaptor shaft by inserting scre wdriver into deep slot and turning coupling 7 turn (push down on screwdriver while turning)Lubricate co upling (f) with Quicksilver Multipurpose Lubricant or Quicksilver 2-4-C Multi-Lube
Longer stud
e"0" Ring 1- Coupling (Shallow SIal Toward Oil Reservoir)