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Required for fitment review to confirm compatibility.
The OBR Mercury/Mariner V6 lower unit is a replacement gearcase for selected 150, 175 and 200 HP outboards. Every configuration on this page uses a 1.87:1 gear ratio. Standard-rotation options are available with 20- or 25-inch shafts for supplier-listed 1979–2018 applications. The remanufactured counter-rotation configuration uses a 25-inch shaft and is listed for applicable 1989–2018 applications.
Fitment cannot be confirmed by horsepower or model year alone. Before ordering, match the complete engine model and serial number, existing OEM number, gear ratio, driveshaft length and rotation. These OBR ME-G6 units are not SEI SE216 or SE218 gearcases and must not be selected using SE216/SE218 fitment data.
New and remanufactured configurations are covered by OBR’s current two-year limited gearcase warranty, subject to its written terms. The lower unit ships without gear oil and must be properly filled, installed and adjusted before operation.
V6 Muscle: Specifically built to handle the high-torque output of 150HP, 175HP, and 200HP powerheads.
Versatile Application: Compatible with a wide range of models from 1979 through 2018.
Saltwater Ready: Advanced marine-grade coating for superior corrosion resistance and long-term protection.
Before dispatch, the selected SKU should be checked against the complete engine model and serial number, existing OEM number, 1.87:1 ratio, shaft length and required rotation. If the submitted information is incomplete or conflicts with the selected configuration, the shipment should be paused and the customer contacted for clarification.
The shipment review should confirm:
The shipping carton, SKU label, driveshaft and skeg area should be inspected before release to the carrier. The customer must be informed that the lower unit ships without gear oil and must be filled with the engine manufacturer’s required lubricant before operation.
When the shipment arrives, inspect the carton for punctures, crushing, water exposure or visible impact. Photograph any damage, retain the carton and packaging, and contact Mariners Warehouse before installation. If serious carrier damage is visible at delivery, refuse the shipment when possible and contact Mariners Warehouse the same day.
| Specification | Mercury Lower Unit | 150-200 HP V6 3.0L | 1.87:1 |
|---|---|
| Manufacturer / brand | OBR Parts & Marine |
| Compatible engine make | Mercury / Mariner |
| Product type | Replacement outboard lower unit / gearcase |
| Engine family | Selected Mercury / Mariner six-cylinder V6 applications |
| Horsepower | 150 HP, 175 HP and 200 HP |
| Conditions | New and remanufactured configurations |
| Standard-rotation years | 1979–2018 supplier-listed applications |
| Counter-rotation years | 1989–2018 supplier-listed applications |
| Rotation | Standard / right-hand and selected counter / left-hand configuration |
| Gear ratio | 1.87:1 |
| Shaft options | 20-inch L and 25-inch XL |
| Standard-rotation SKUs | ME-G6-08A-N, ME-G6-08A-R, ME-G6-09A-N and ME-G6-09A-R |
| Counter-rotation SKU | ME-G6-10A-R |
| 20-inch OEM references | 9148T84, 9148A84 and 9148A90 |
| 25-inch standard OEM references | 9148T85, 9148A85, 9148A91 and 9148T91 |
| 25-inch counter OEM references | 9148T86, 9148A86, 9148A92 and 9148T92 |
| Gear oil | Ships without gear oil; fill with the engine manufacturer's required lubricant before operation |
| Warranty | Two-year OBR limited warranty; written terms and exclusions apply |
| Required fitment data | Complete engine model and serial number, horsepower, year, existing OEM number, ratio, shaft length and rotation |
| Major exclusions | Do not assume SE216, SE218, 3.0L Optimax, Torque Master, Sport Master or Verado compatibility without supplier verification |
Choosing the correct Mercury V6 lower unit requires matching the complete configuration—not simply finding a listing with the same horsepower. Begin by confirming that the original gearcase uses a 1.87:1 gear ratio. Installing a different ratio can change engine load and operating RPM even when the replacement appears to bolt onto the midsection.
Next, verify the driveshaft length. The standard-rotation OBR configurations on this page are available with either a 20-inch L or 25-inch XL shaft. The current counter-rotation option is a remanufactured 25-inch unit listed for applicable 1989–2018 applications. Rotation must be matched to the existing gearcase and propeller setup; engine position alone is not sufficient proof.
Finally, compare the existing OEM number with the references in the compatibility table and submit the complete engine model and serial number. Do not select these units using SEI SE216 or SE218 specifications, and do not assume that a 3.0L, Optimax, Torque Master, Sport Master or Verado application is compatible without confirmation.
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The product details made it very easy to confirm the correct gearcase for my Mercury 175 HP 3.0L V6. Matching the 1.87:1 gear ratio, 20-inch shaft length, and checking engine serial numbers made all the difference. Verifying gear ratio before buying is essential.
I appreciated how clearly the 3.0L V6 150–200 HP options were separated from the smaller 2.5L blocks. Mariners Warehouse support helped check my serial number and verified the 1.87:1 ratio prior to shipping.
The lower unit arrived securely packaged with heavy foam reinforcement. The drive shaft splines, shift rod, and 25-inch shaft length lined up seamlessly on my 200 HP 3.0L V6 engine. Runs smooth and quiet following proper break-in.
Identifying the 1.87:1 ratio and shaft length was straightforward. The lower unit handles great on the water, though unbolting the heavy shipping crate and setting the shift height took a bit of extra time.
Replaced the worn lower unit on my 150 HP 3.0L Mercury. The product listing outlined all shaft lengths and fluid specs clearly. After filling with high-performance marine lube and running through break-in hours, it performs flawlessly.
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