Mercury - Drain Screw Seals Gear Case Components Rubber-Coated Stainless Steel 8M0183616 (Pack of 4). Overview. There's a quiet kind of confidence that comes from knowing your gear case is sealed tight and protected from the water you're running through. It's one of those small details that doesn't cross your mind during a long day on the bay - and that's exactly how it should be. These Mercury Marine parts help keep things that way. Whether you're cruising across glass-calm water or bouncing th