2003+ Suzuki DF9.9/DF15 four stroke outboard motors service manual, Page 180Get this manual
LOWER UNIT 8-15
Install the dog spring 4, ensuring that it fits snugly into the groove on the clutch dog shifter
FORWARD GEAR Apply the gear oil to the forward gear and place the back-up shim in position, then install the forward gear 99000-22540: SUZUKI OUTBOARD MOTOR GEAR OIL