Mercury - Quicksilver Exhaust Manifold Gasket Exhaust System Seal Marine-Grade Composite 46820. Overview. When you're dealing with a high-performance marine V8, a tight exhaust seal isn't optional - it's essential. The Mercury Marine 46820 Quicksilver Exhaust Manifold Gasket is built for General Motors-based V8 engines used in MerCruiser sterndrives and inboard applications. It's also compatible with similar CID engines from OMC and Volvo Penta. Made from durable, marine-tested composite materia