Mercury - Quicksilver Exhaust Elbow Exhaust System Part In-Line 6-Cylinder MerCruiser Engines 76351A04. Overview. If you're bringing an older MerCruiser back to life, this is one of those parts that makes a real difference. The Mercury Marine 76351A04 Quicksilver Exhaust Elbow is built to factory specs for MerCruiser in-line six-cylinder engines, including the 140 (1966-1982), 470 (1976-1977), 165, and 200 models. It's tough, reliable, and designed to handle the constant heat, water, and vibrati