Mercruiser Bravo SE121 Complete Drive (Replaces Bravo One) Lower Unit
Mercruiser Bravo SE121 Complete Drive (Replaces Bravo One) Lower Unit Original price was: $3,990.45.Current price is: $3,595.00.
Back to products
Yamaha 4 Stroke 115-130 HP
Yamaha Aftermarket Lower Unit – Replaces 115–130HP 4 Stroke – Fits 20" & 25" Shafts – SEI 90-405 Original price was: $1,326.45.Current price is: $1,195.00.

Yamaha Aftermarket Lower Unit – Replaces 75–100HP 2/4 Stroke – 2.0 & 2.3 Gear Ratios – 18 Spline – 20″ & 25″ Shafts – SEI 90-404

(26 customer reviews)

Original price was: $1,326.45.Current price is: $1,195.00.

Search your model no. for perfect fit

✔️
Manufacturer Warranty: 3-Year

✔️
Return Policy: 7 – 14 day, hassle-free returns

✔️
Trusted by 6,000+ boaters across the USA

🎉 Hurry Up! Use code WELCOME5 to get an extra 5% OFFOffer expires soon!
SKU: ST-90-404 Categories: , , ,
Description

Replaces some Yamaha 2-stroke and 4-stroke 75-100 HP Standard Rotation Lower Units.
Does not fit 2016-present 4 stroke engine models ending in “B”
The paint color is Black. You can paint it to match.

Use CRTL+F to Search for your Engine Model Number

For — 2:1 Ratio / 20″ Shaft / 2 Stroke / RH Rotation

Year Model Number Shaft Gear Ratio SEI part number
2009 90TLR 20 2:1 90-404-A20
2008 90TLR 20 2:1 90-404-A20
2007 90TLR 20 2:1 90-404-A20
2006 90TLR 20 2:1 90-404-A20
2005 90TLR 20 2:1 90-404-A20
2005 90TLRD 20 2:1 90-404-A20
2004 90TLRC 20 2:1 90-404-A20
2003 90TLRB 20 2:1 90-404-A20
2002 90TLRA 20 2:1 90-404-A20
2001 C90TLRZ 20 2:1 90-404-A20
2001 90TLRZ 20 2:1 90-404-A20
2000 C90TLRY 20 2:1 90-404-A20
2000 90TLRY 20 2:1 90-404-A20
2000 E75MLHY 20 2:1 90-404-A20
1999 C90TLRX 20 2:1 90-404-A20
1999 B90TLRX 20 2:1 90-404-A20
1999 90TLRX 20 2:1 90-404-A20
1999 C75TLRX 20 2:1 90-404-A20
1999 E75MLHX 20 2:1 90-404-A20
1999 P75TLHX 20 2:1 90-404-A20
1998 C90TLRW 20 2:1 90-404-A20
1998 90TLRW 20 2:1 90-404-A20
1998 B90TLRW 20 2:1 90-404-A20
1998 C75TLRW 20 2:1 90-404-A20
1998 E75MLHW 20 2:1 90-404-A20
1998 P75TLHW 20 2:1 90-404-A20
1997 C90TLRV 20 2:1 90-404-A20
1997 B90TLRV 20 2:1 90-404-A20
1997 90TLRV 20 2:1 90-404-A20
1997 E75MLHV 20 2:1 90-404-A20
1997 P75TLHV 20 2:1 90-404-A20
1997 C80TLRV 20 2:1 90-404-A20
1996 90TLRU 20 2:1 90-404-A20
1996 C75TLRU 20 2:1 90-404-A20
1996 E75MLHU 20 2:1 90-404-A20
1996 P75TLHU 20 2:1 90-404-A20
1996 C85TLRU 20 2:1 90-404-A20
1995 90TLRT 20 2:1 90-404-A20
1995 C75TLRT 20 2:1 90-404-A20
1995 E75MLHT 20 2:1 90-404-A20
1995 C85TLRT 20 2:1 90-404-A20
1994 90TLRS 20 2:1 90-404-A20
1994 C75TLRS 20 2:1 90-404-A20
1994 C85TLRS 20 2:1 90-404-A20
1993 90TLRR 20 2:1 90-404-A20
1993 C85TLRR 20 2:1 90-404-A20
1992 90TLRQ 20 2:1 90-404-A20
1992 C85TLRQ 20 2:1 90-404-A20
1991 90TLRP 20 2:1 90-404-A20
1991 C85TLRP 20 2:1 90-404-A20
1990 90ETLD 20 2:1 90-404-A20
1990 90ETLDA 20 2:1 90-404-A20
1990 CV85ETLD 20 2:1 90-404-A20
1990 CV85ELD 20 2:1 90-404-A20
1989 90ETLF 20 2:1 90-404-A20
1989 CV85ELF 20 2:1 90-404-A20
1988 90ETLG 20 2:1 90-404-A20
1987 90ETLH 20 2:1 90-404-A20
1986 90ETLJ 20 2:1 90-404-A20
1985 90ETLK 20 2:1 90-404-A20
1984 90ETLN 20 2:1 90-404-A20

 

For – 2.3:1 Ratio / 20″ Shaft / 4-Stroke

Replaces some F75, F80, F90 and F100 Yamaha gear cases on 4-Stroke Engines with 20 inch drive shaft.
Does not fit 2016-present 4 stroke engine models ending in “B”
The color is Black. You can paint it to match.
See Technical tab to see if your specific model is listed.

Year Model Number Shaft Gear Ratio SEI part number
2017 F90LA 20 2.3:1 90-404-B20F
2017 F75LA 20 2.3:1 90-404-B20F
2016 F90LA 20 2.3:1 90-404-B20F
2016 F75LA 20 2.3:1 90-404-B20F
2015 F90LA 20 2.3:1 90-404-B20F
2015 F75LA 20 2.3:1 90-404-B20F
2014 F90LA 20 2.3:1 90-404-B20F
2014 F75LA 20 2.3:1 90-404-B20F
2013 F90LA 20 2.3:1 90-404-B20F
2013 F75LA 20 2.3:1 90-404-B20F
2012 F90LA 20 2.3:1 90-404-B20F
2012 F75LA 20 2.3:1 90-404-B20F
2011 F90TLR 20 2.3:1 90-404-B20F
2011 F75TLR 20 2.3:1 90-404-B20F
2010 F90TLR 20 2.3:1 90-404-B20F
2010 F75TLR 20 2.3:1 90-404-B20F
2009 F90TLR 20 2.3:1 90-404-B20F
2009 F75TLR 20 2.3:1 90-404-B20F
2008 F90TLR 20 2.3:1 90-404-B20F
2008 F75TLR 20 2.3:1 90-404-B20F
2007 F90TLR 20 2.3:1 90-404-B20F
2007 F75TLR 20 2.3:1 90-404-B20F
2006 F90TLR 20 2.3:1 90-404-B20F
2006 F75TLR 20 2.3:1 90-404-B20F
2005 F90TLR 20 2.3:1 90-404-B20F
2005 F90TLRD 20 2.3:1 90-404-B20F
2005 F75TLR 20 2.3:1 90-404-B20F
2005 F75TLRD 20 2.3:1 90-404-B20F
2004 F90TLRC 20 2.3:1 90-404-B20F
2004 F75TLRC 20 2.3:1 90-404-B20F
2003 F90TLRB 20 2.3:1 90-404-B20F
2003 F100TLRB 20 2.3:1 90-404-B20F
2003 F75TLRB 20 2.3:1 90-404-B20F
2003 F80TLRB 20 2.3:1 90-404-B20F
2002 F100TLRA 20 2.3:1 90-404-B20F
2002 F80TLRA 20 2.3:1 90-404-B20F
2001 F100TLRZ 20 2.3:1 90-404-B20F
2001 F80TLRZ 20 2.3:1 90-404-B20F
2000 F100TLRY 20 2.3:1 90-404-B20F
2000 F80TLRY 20 2.3:1 90-404-B20F
1999 F100TLRX 20 2.3:1 90-404-B20F
1999 F80TLRX 20 2.3:1 90-404-B20F

 

For – 2.3:1 Ratio / 25″ Shaft / 4-Stroke

Replaces some F80, F90 and F100 Yamaha gear cases on 4-Stroke Engines with 25 inch drive shaft.
Does not fit 2016-present 4 stroke engine models ending in “B”
The color is Black. You can paint it to match.
See Technical tab to see if your specific model is listed.

Year Model Number Shaft Gear Ratio SEI part number
2017 F90XA 25 2.3:1 90-404-B25F
2016 F90XA 25 2.3:1 90-404-B25F
2015 F90XA 25 2.3:1 90-404-B25F
2014 F90XA 25 2.3:1 90-404-B25F
2013 F90XA 25 2.3:1 90-404-B25F
2012 F90XA 25 2.3:1 90-404-B25F
2011 F90TXR 25 2.3:1 90-404-B25F
2010 F90TXR 25 2.3:1 90-404-B25F
2009 F90TXR 25 2.3:1 90-404-B25F
2008 F90TXR 25 2.3:1 90-404-B25F
2007 F90TXR 25 2.3:1 90-404-B25F
2006 F90TXR 25 2.3:1 90-404-B25F
2005 F90TXR 25 2.3:1 90-404-B25F
2005 F90TXRD 25 2.3:1 90-404-B25F
2003 F100TXRB 25 2.3:1 90-404-B25F
2002 F100TXRA 25 2.3:1 90-404-B25F
2001 F100TXRZ 25 2.3:1 90-404-B25F
2000 F100TXRY 25 2.3:1 90-404-B25F
2000 F80TXRY 25 2.3:1 90-404-B25F
1999 F100TXRX 25 2.3:1 90-404-B25F
1999 F80TXRX 25 2.3:1 90-404-B25F
Additional information
Weight 65 lbs
Dimensions 37 × 10 × 61 in
Ratio/Shaft/Motor

2.0 Ratio/20" 18 spline/2-Stroke/RH Rotation

,

2.3 Ratio/20" 18 Spline/4-Stroke

,

2.3 Ratio/25" 18 Spline/4-Stroke

Brand

Brand

Yamaha

Reviews (26)
3.9
26 reviews
8
7
11
0
0

26 reviews for Yamaha Aftermarket Lower Unit – Replaces 75–100HP 2/4 Stroke – 2.0 & 2.3 Gear Ratios – 18 Spline – 20″ & 25″ Shafts – SEI 90-404

Clear filters
  1. Pamela Gibson

    No special tools needed. Done in a coffee break!

  2. Taylor Hendrix

    The unit’s grease ports are strategically placed for easy maintenance. Installed it in 40 minutes, and performance has been flawless. OEM should take notes!

  3. John Simmons

    No more overheating issues. Runs like new!

  4. Alexander Wood MD

    Why I waited so long? This unit revived my boat. Smooth, reliable, affordable. Don’t hesitate—buy it now!

  5. Edward Smith

    Rugged housing handles storms. Budget-friendly beast!

  6. Darren Wells

    The packaging included foam inserts to prevent shipping damage. Installation was tool-free, and the unit meshes perfectly with my motor. No leaks or noise—highly recommend!

  7. April Watson

    The included torque specs ensured a proper installation. Two months later, the unit performs like new—no noise, no leaks, no regrets. A perfect aftermarket solution!

  8. Emily Lopez

    The packaging included foam inserts to prevent rattling during transit. Installation took 30 minutes, and the unit meshes perfectly with my motor. No vibrations or leaks—extremely impressed!

  9. Emily Parks

    The unit’s grease fittings made maintenance a breeze. Installation took 40 minutes, and performance has been flawless through 15 hours of runtime. OEM should take notes!

  10. Megan Gonzales

    I’ve used this in both freshwater and salt—zero issues. The stainless steel components stay pristine, and the shifts are crisp. A reliable, affordable solution!

  11. Robin Washington

    Mounted yesterday—handled a full day on the water flawlessly.

  12. Amber Le

    Survived saltwater testing—zero corrosion. Solid engineering!

  13. Mr. Nathan Hernandez

    Perfect for DIYers. Saved $$$ on mechanic fees.

  14. Veronica Cox

    The customer team replied to my midnight query in minutes! The unit is quiet, durable, and leak-proof. A standout in aftermarket parts—highly recommend!

  15. Anne Thornton

    Tested this in icy lakes and tropical waters—no issues. The stainless steel gears handle temperature swings effortlessly, and the shifts stay precise. A four-season workhorse!

  16. Aaron Jackson Jr.

    Everything arrived securely packaged with all hardware included. Installation was a breeze—no missing parts or confusing steps. After two months of heavy use, it still runs like new. Worth every penny!

  17. Johnny Greene

    This unit survived a month-long expedition in Alaskan waters. No corrosion, no leaks, and shifts are as smooth as day one. OEM engineers should take notes!

  18. Danielle May

    Reduced vibration by 90%. Feels factory-new!

  19. Carrie Jones

    Great support—quiet and durable. Standout product!

  20. James Watts

    The unit’s powder-coated finish resists chips and scratches. Installation took 35 minutes, and performance is flawless. Why spend more on overpriced OEM parts?

  21. Andrea Stephens

    I’ve tested this unit in saltwater for three weeks, and there’s no sign of corrosion. The gears engage smoothly, and it’s noticeably quieter than my old OEM part. Highly recommend for marine use!

  22. Kimberly Morris

    Not a single leak. Performs like it’s brand new.

  23. Kimberly Patterson

    Direct replacement—no modifications needed. Works perfectly!

  24. Eric Calhoun

    This unit saved my boating season. Installed in under an hour, it’s outperformed my old OEM part with smoother shifts and better fuel efficiency. Worth every cent!

  25. Jamie Vaughn

    Pre-greased fittings saved me 30 minutes of messy work. Installed solo, and it’s been flawless through 50 hours of runtime. DIYers, this is your holy grail!

  26. Shannon Jacobs

    Installed this on a 2005 motor—fit like a glove. Smooth engagement, no vibrations, and saved $700. Vintage boaters, this is your fix!

Only logged in customers who have purchased this product may leave a review.

Shipping & Delivery

Fast Delivery with FedEx

We understand that getting your products quickly is important. Our partnership with FedEx guarantees:

  • Speedy Shipping: Reliable, fast delivery to get your order to you in no time.
  • Real-Time Tracking: Stay updated with the status of your shipment every step of the way.

Secure Checkout Options

We’ve made online shopping safe and simple by offering trusted payment options:

  • Credit Cards/Debit Cards: We accept all major credit cards & Debit Cards with encrypted, secure processing to protect your sensitive data.