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Required for fitment review to confirm compatibility.
The Suzuki SE521 lower unit is a new aftermarket standard-rotation replacement gearcase manufactured by SEI for selected Suzuki DF200, DF225 and DF250 3.6L V6 outboards.
Available configurations include a 25-inch driveshaft under SKU 90-521-B25F and a 30-inch driveshaft under SKU 90-521-B30F. Both configurations use a 2.29:1 overall ratio with a 12/22 gear-tooth combination.
The SE521 is designed for verified standard or right-hand rotation TX/TXX applications. It must not be used as a replacement for counter-rotation, left-hand or Suzuki AP-model gearcases.
Fitment cannot be confirmed using horsepower alone. Before ordering, provide the complete Suzuki engine model, serial number, model year, required rotation and shaft length.
The Suzuki SE521 lower unit is intended for selected standard-rotation TX and TXX applications:
The selected SKU must match the required 25-inch or 30-inch driveshaft configuration.
Additional suffixes such as TXW, TL, TXK4–K10 and TXXK4–K10 must be verified against current SEI fitment information before they are listed as compatible.
Always confirm the complete engine model, serial number, model year, shaft length and required rotation before ordering.
Before ordering, submit the complete engine model, serial number, model year, rotation and shaft length.
Before dispatch, your SE521 order is reviewed to help confirm the selected configuration and identify obvious fitment conflicts.
Important: This review does not replace professional installation verification. The installer must confirm the engine model, serial number, rotation and shaft length before installation.
| Specification | Suzuki SE521 Standard-Rotation Lower Unit for DF200, DF225 & DF250 |
|---|---|
| Product | New aftermarket replacement gearcase |
| Manufacturer | SEI |
| Engine family | Selected Suzuki 3.6L V6 four-strokes |
| Models | Selected DF200, DF225 and DF250 |
| Rotation | Standard/right-hand only |
| Overall ratio | 2.29:1 |
| Gear teeth | 12/22 |
| Shaft options | 25-inch and 30-inch |
| Model designations | Verified TX/TXX applications |
| DF200 years | 2004–2014 |
| DF225/DF250 years | 2004–current |
| Exclusion | Does not replace AP models |
| 25-inch SKU | 90-521-B25F |
| 30-inch SKU | 90-521-B30F |
The Suzuki SE521 lower unit is a standard-rotation replacement gearcase for selected 3.6L V6 DF200, DF225 and DF250 outboards. SEI offers this aftermarket Suzuki lower unit in both 25-inch and 30-inch configurations, with a 2.29:1 overall ratio and 12/22 gear-tooth combination.
The SE521 should be used only for verified standard or right-hand rotation applications. It must not be confused with the SE528 counter-rotation lower unit. Engine position alone does not reliably identify the correct gearcase, especially on twin- or multi-engine boats.
Before ordering a Suzuki DF200, DF225 or DF250 lower unit, confirm the complete engine model, serial number, model year, required rotation and driveshaft length. The SE521 does not replace Suzuki AP models, and its DF200 application is limited to selected 2004–2014 engines.
Use CTRL + F or search below to find your engine model
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Ordered the Suzuki SE521 lower unit for my DF225, and the fit was exactly what I needed. The standard rotation setup matched my application, and everything went together cleanly. Very happy with the replacement, and the motor is back on the water.
I needed a Suzuki replacement gearcase after damaging my original lower unit. The SE521 lower unit was a good aftermarket option for my Suzuki, and the 2.29:1 setup matched what I needed. Installation went smoothly after confirming the fitment.
I was looking for an aftermarket Suzuki lower unit instead of rebuilding my damaged gearcase. The SE521 has been a solid replacement so far, and the standard rotation configuration was correct for my setup. Definitely recommend checking your model and shaft length before ordering.
Needed a Suzuki 30-inch lower unit for my outboard and went with the SE521 after checking the engine information. Fitment was straightforward, and the gearcase has been running smoothly. Having the 25-inch and 30-inch options made it easier to get the correct configuration.
My original gearcase was damaged, and I needed a Suzuki outboard lower unit replacement without going through a complete rebuild. The SE521 standard rotation lower unit fit the application well and got the boat back in service. So far, I am very pleased with the replacement.
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