# 6h3-45300-1a-8d Yamaha gearbox - 20 inch | Genuine Used Part

🔧 Product Description

  

Genuine Yamaha 20-Inch Lower Unit - Part Number: 6H3-45300-1A-8D

  

A genuine used Yamaha complete long-shaft gearbox for 60HP and 70HP two-stroke outboards, with selected related 50HP applications. The 6H3-45300-1A-8D assembly belongs to Yamaha's durable mid-range three-cylinder lower-unit family and is superseded in service catalogues by 6H3-45300-19-8D.

  

⚙️ Key Features

  

• Genuine Yamaha complete lower-unit assembly

• Original part number 6H3-45300-1A-8D

• 20-inch long-shaft configuration

• Used primarily on 60HP and 70HP two-strokes

• Current related service assembly 6H3-45300-19-8D

  

🔄 Supersession & Cross Reference

  

OEM Supersession Chain:

  

• 6H3-45300-19-8D supersedes 6H3-45300-1A-8D

• The 19-8D service unit also consolidates earlier 10-EK through 19-4D revisions

• Later 6H3-45300-20-8D units may suit selected engines but require diagram confirmation

  

OEM / Related Numbers:

  

• 6H3-45300-1A-8D

• 6H3453001A8D

• 6H3-45300-19-8D

• 6H3-45300-19-4D

• 6H3-45300-15-4D

• 6H3-45300-14-4D

• 6H3-W0001-22 / 6H3-W0001-C1 seal-kit family

• 6H3-W0078-01 water-pump repair kit

  

Aftermarket / Verified Equivalents:

  

• New aftermarket 6H3-45300-20-8D-pattern 60HP-70HP long-shaft lower units

• Professionally remanufactured Yamaha 60HP / 70HP gearcases

• Sierra 18-3069 or equivalent impeller replacing 6H3-44352-00

• Aftermarket 6H3 seal, bearing and gear sets

• Replacement skegs, skeg guards and propeller-shaft seals

  

🚤 Compatibility

  

Commonly used on:

  

• Yamaha 60F, P60 and 70B two-stroke engines

• Yamaha 60FETO / 60TLR / 70BETO / 70TLR

• Selected 50HP three-cylinder models using the 6H3 lower-unit family

  

Typically suits:

  

• Confirmed diagrams include 1986-1993 60HP and 70HP engines

• Later 60TLR and 70TLR engines continue to use related 6H3 units

• Regional production may extend into the late 2000s

• Verify gear ratio and shift-shaft height because several 6H3 revisions exist

  

• HP Range: Approximately 50HP - 70HP

• Shaft Length: 20 inches / L

• Gear Ratio: Model-dependent; commonly around 2.33:1 in this family

• Rotation: Standard right-hand

• Fitment Requirement: Confirm complete service number, driveshaft length and propeller-shaft spline

  

🔌 Function

  

The lower unit reduces engine speed to the propeller, provides forward-neutral-reverse selection and houses the cooling-water pump.

  

Common signs of failure:

  

• Gear noise or rough rotation

• Water entering the gear oil

• Worn clutch dog or shift cam

• Bent driveshaft or propeller shaft

• Broken skeg or corroded housing

  

📦 Condition

  

• Genuine used part

• Removed from running engine or vessel where applicable

• In good working condition unless otherwise stated

## Details

- **Price:** 425.0 AUD
- **Vendor:** Sawley's Auto and Marine
- **Tags:** Sawley’s AAM Used Parts – Outboard Gearboxes (Complete Units) | Lower Units & Gearcases

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 425.00 AUD | In stock |

## Images

- 6h3-45300-1a-8d Yamaha gearbox - 20 inch | Genuine Used Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/6h3-45300-1a-8d-yamaha-gearbox-20-inch-genuine-used-part)
> Updated: 2026-07-20