Suzuki 2002-2005 DF4/DF5/DF6 4-Stroke Outboards Service Manual, Page 132Get this manual
LOWER UNIT 8-11
Make sure that all parts used in assembly are clean and lubricated After assembly, check the parts for tightness and smoothness of operation Before final assembly, be absolutely certain that all gear contact, shim adjustments and tolerances are correctFailure to correctly adjust these areas will result in lower unit damage(See the "LOWER UNIT GEARS-SHIMMING AND ADJUSTMENT" section on the page 8-17 Do not re-use the gasket, the O-ring and the cotter pin once removedAlways use new parts
FORWARD GEAR
Apply the gear oil to the following parts Forward gear backup shim Forward gear Forward gear thrust washer 99000-22540Suzuki Outboard Motor Gear Oil