6H1-45300-17-8D Yamaha 20" Long Shaft Gearbox | Genuine Used Part

🔧 Product Description

Genuine Yamaha 20-Inch Lower Unit - Part Number: 6H1-45300-17-8D

A genuine used Yamaha complete long-shaft lower unit for 75HP, 80HP, 85HP and 90HP three-cylinder two-stroke outboards. This 20-inch 6H1 assembly is the later service version of a long-running gearcase family used from the mid-1980s through the late 2000s.

⚙️ Key Features

• Genuine Yamaha complete 6H1 lower unit
• Correct part number 6H1-45300-17-8D
• 20-inch long-shaft configuration
• Used on 75HP to 90HP two-stroke engines
• Later replacement for numerous 6H1 service revisions

🚤 Compatibility

Commonly used on

• Yamaha 75A / 75B / E75 two-stroke outboards
• Yamaha 80A / 85A / E85 engines
• Yamaha 90A / 90TLR / 90AETO engines
• 20-inch standard-rotation three-cylinder gearcases

Typically suits

• Confirmed used-part and catalogue coverage from approximately 1984-2008
• 75HP, 80HP, 85HP and 90HP three-cylinder Yamaha two-strokes
• Remote-control, tiller, Enduro and selected commercial configurations
• HP Range: Approximately 75HP - 90HP
• Shaft Length: 20 inches / L
• Gear Ratio: Commonly 2.00:1; verify tooth count
• Rotation: Standard right-hand
• Fitment Requirement: Confirm model prefix 6H1, driveshaft length and shift-shaft arrangement

🔌 Function

The lower unit provides gear reduction, forward-neutral-reverse selection, propeller drive and cooling-water pumping for the outboard.

⚠️ Common Signs of Failure

• Whining or rumbling bearings
• Water or metal in the lubricant
• Hard or incomplete gear engagement
• Bent propeller shaft
• Damaged skeg, cavitation plate or gearcase housing

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 6H1-45300-17-8D replaces 6H1-45300-16-8D and 6H1-45300-16-EK
• Also supersedes selected 6H1-45300-10 through 15 EK, 4D and 8D assemblies
• Older export and colour suffixes must be matched by shaft length and rotation

OEM / Related Numbers

• 6H1-45300-17-8D
• 6H145300178D
• 6H1-45300-16-8D
• 6H1-45300-16-EK
• 6H1-45300-15-8D
• 6H1-45300-15-4D
• 6H1-45300-14-4D
• 6H1-W0001-series seal kit

Aftermarket / Verified Equivalents

• SEI Marine SE404-family Yamaha 75HP-100HP replacement lower unit where shaft, ratio and shift system match
• Professionally remanufactured Yamaha 75HP-90HP 20-inch gearcases
• Aftermarket gear, bearing and seal kits
• Sierra / Recmar water-pump kits for the 6H1 family
• Aftermarket skeg guards and replacement skeg sections

📦 Condition

• Genuine used part
• Removed from running engine or vessel where applicable
• In good working condition unless otherwise stated