Mercury – Complete Gearcase | SeaCore Bravo One / One X Series | Hard-Coat Anodized Alloy | 8866J01

Overview
Anyone who’s spent long days offshore knows how much trust you place in your gearcase. It’s the muscle under the boat—quiet, steady, and often forgotten until something goes wrong. When it’s right, you can feel it in every clean shift and every smooth rise onto plane. The Mercury Marine part number 8866J01 Complete Gearcase brings that confidence back to your MerCruiser SeaCore Bravo One or One X sterndrive, giving you the peace of mind that only a well-built, saltwater-ready drive can offer. Whether you’re carving through an inlet or cruising toward open horizon, this gearcase is designed to carry you there with strength you can trust.

Key Features

• Complete replacement gearcase built for MerCruiser SeaCore Bravo One and One X sterndrives

• SeaCore hard-coat anodized housing for exceptional corrosion resistance in harsh saltwater use

• Tri-Paint exterior system adds a durable, multi-layer protective barrier

• XK360 low-copper alloy for additional corrosion defense

• Heavy-duty forged gears and reinforced U-joint for long service life

• Compatible with 1.36, 1.50, and 1.65 gear ratios

Engine & Boat Compatibility

• Fits MerCruiser SeaCore Bravo One and Bravo One X sterndrives

• Built for marine power systems using 1.36, 1.50, and 1.65 gear ratios

• Ideal for performance boats, offshore fishing boats, sport cruisers, and high-torque recreational vessels

• Works in both single-engine and twin-engine setups

Performance & Practical Benefits
A gearcase is one of those components where quality shows itself instantly. With the 8866J01 installed, shifts feel decisive and clean, free from hesitation or chatter. Under load, the forged gears deliver a strong, smooth transfer of power that gives the boat a steadier ride—especially when you’re accelerating hard or running through chop. You’ll feel how tight and secure everything is, as if the whole drive suddenly gained a new backbone.

Then there’s the corrosion resistance. Saltwater can be ruthless, eating away at anything that’s not built to stand up to it. The SeaCore hard-coat anodizing, Tri-Paint protection, and low-copper alloy all work together to create a barrier that holds up season after season. It’s the kind of durability that lets you focus on the water instead of worrying about what’s happening beneath it. Installation is straightforward for a complete assembly like this, and once it’s bolted in, it’s built to remain steady and reliable with minimal upkeep.

Why Buy OEM
When you’re replacing an entire gearcase, choosing genuine OEM isn’t just a preference—it’s a smart investment. A Mercury Marine part like this one is engineered to fit perfectly, run smoothly, and hold up under conditions the designers anticipated from day one. Aftermarket assemblies can look similar, but differences in materials, machining, and coating become obvious once the drive is in the water. With OEM, you get matched tolerances, proven durability, and the reliability that comes from decades of marine engineering. If you want your sterndrive to feel right the first time—and stay that way—OEM is the way to go.

FAQ
Q1: Which systems does the Complete Gearcase 8866J01 fit?
It fits MerCruiser SeaCore Bravo One and One X sterndrives with 1.36, 1.50, or 1.65 gear ratios.

Q2: What makes this better than aftermarket versions?
The corrosion protection and gear construction. Mercury’s hard-coat anodizing, Tri-Paint finish, and forged gears deliver long-term reliability aftermarket gearcases usually can’t match.

Q3: How do I confirm this is the right replacement?
Match your sterndrive model (Bravo One or One X) and verify your gear ratio. If those line up, this part number is typically the correct fit.

Q4: Can it be used in freshwater and saltwater?
Absolutely. It’s built for the harshest saltwater environments, so freshwater use is well within its capabilities.

Q5: Is installation straightforward?
For experienced boat owners or technicians, yes. It installs like a standard Bravo One gearcase replacement with predictable fitment.