Experiencing engine hesitation or reduced power? This authentic Mercury Marine GEAR HOUSING ASSEMBLY, Basic solves the problem with factory precision – no guessing, no compromises.

Built with Mercury Marine’s precision engineering, this housing assembly ensures reliable operation across all engine RPM ranges. Part number 859399T18 is manufactured to exact Mercury Marine factory specifications for precision installation and optimal performance. Constructed from premium marine-grade materials designed to withstand harsh saltwater and freshwater environments.

Smart boat owners know: buying cheap parts twice costs more than buying genuine Mercury once. Part 859399T18 delivers long-term value through superior materials and precision manufacturing.

Compatible Mercury Marine Engines

FITS: 200-225HP MARINER, MERCURY

• Fits MARINER, MERCURY 200-225HP engines
• Compatible HP: 200HP, 225HP
• Covers 24 serial number ranges
• Configurations: Outboard
• OEM genuine Mercury Marine part

COMPLETE SERIAL NUMBER COMPATIBILITY:

200HP Models

• 200HP OUTBOARD (Mariner): 0T750164-0T800999, 0T801000-1B417701, 0G960500-0T178499, 0T178500-0T598999, 0T599000-0T800999, 0T801000-1B417701, 1B417702-1B504988
• 200HP OUTBOARD (Mercury): 0T980000-1B417701, 1B417702-1B504988, 0T750164-0T800999, 0T801000-1B417701, 1B417702-1B504988, 0G960500-0T178499, 0T178500-0T598999, 0T599000-0T800999, 0T801000-1B417701, 1B417702-1B504988

225HP Models

• 225HP OUTBOARD (Mariner): 0G760300-0T408999, 0G760300-0T408999, 0T409000-0T800999, 0T801000-1B417701
• 225HP OUTBOARD (Mercury): 0G760300-0T408999, 0G760300-0T408999, 0T409000-0T800999

Don’t know where your serial number is? Our quick reference guide shows exactly where to find it on Mercury Marine engines.

Verification & Support

Not sure if part 859399T18 fits your engine? Try our parts finder tool — it’s quick and easy. Need expert help? Contact us using the buttons at the bottom of this page – text, call, or email, whatever works best for you

Serving boaters for over 40 years. Great prices, quick delivery – your parts ship fast.