Mercury - 300 Hour Maintenance Kit MerCruiser 4.3L Carbureted Alpha Drive OEM Service Components 8M0147063. Overview. If you run a MerCruiser 4.3L carbureted engine, you know exactly what it feels like when that V6 is dialed in just right-smooth throttle, clean exhaust note, and the steady push that lets you relax into a long stretch of open water. The Mercury 8M0147063 300 Hour Maintenance Kit is built for boaters who want to keep that feeling going. Everything in this kit supports the health,