1999 40hp 2 stroke 3 cylinder 20" gearcase ready to run fits:

This Mercury 821306A28 GEAR HOUSING ASSEMBLY *{ (BLACK) LONG}* fits the following models and components:

Mercury Outboard 40HP 40HP 9973100 THRU 0P016999 Gear Housing (Driveshaft)(1.83:1 Gear Ratio)

Mercury Outboard 50HP 50HP 9973100 THRU 0P016999 Gear Housing (Driveshaft)(1.83:1 Gear Ratio)

Mercury Outboard 30HP 30HP JET 9973100 THRU 0P016999 Gear Housing (Driveshaft)(1.83:1 Gear Ratio)

Mercury Outboard 40HP 40HP 0G590000 THRU 0G760299 Gear Housing (Driveshaft)(1.83:1 Gear Ratio)

Mercury Outboard 50HP 50HP 0G590000 THRU 0G760299 Gear Housing (Driveshaft)(1.83:1 Gear Ratio)

Mercury Outboard 30HP 30HP JET 0G590000 THRU 0G760299 Gear Housing (Driveshaft)(1.83:1 Gear Ratio)

Mercury Outboard 40HP 40HP 9973100 THRU 0P016999 Gear Housing, Propeller Shaft - 1.83:1 Gear Ratio

Mercury Outboard 50HP 50HP 9973100 THRU 0P016999 Gear Housing, Propeller Shaft - 1.83:1 Gear Ratio

Mercury Outboard 30HP 30HP JET 9973100 THRU 0P016999 Gear Housing, Propeller Shaft - 1.83:1 Gear Ratio

Mercury Outboard 40HP 40HP 0G590000 THRU 0G760299 Gear Housing, Propeller Shaft - 1.83:1 Gear Ratio

Mercury Outboard 50HP 50HP 0G590000 THRU 0G760299 Gear Housing, Propeller Shaft - 1.83:1 Gear Ratio

Mercury Outboard 30HP 30HP JET 0G590000 THRU 0G760299 Gear Housing, Propeller Shaft - 1.83:1 Gear Ratio