Mercury - Transmission Filter V12 Two-Speed System Stainless Steel Element 8M0177646. Overview. When you run a Mercury V12 offshore, you learn to appreciate every part that keeps that power seamless and predictable. The two-speed transmission is one of those quiet heroes-you hardly notice it shifting, but you feel the steady push as the boat rises and settles into its groove. That smooth confidence only happens when the internal components are protected and kept clean. The Mercury 8M0177646 Tran