Mercury - ACDelco MR43LTS Marine Spark Plug Specialty Marine Ignition Series Nickel Alloy & Copper Core 862029. Overview. There's something satisfying about a marine engine that fires up instantly-a crisp spark, a steady rumble, and the quiet assurance that today's trip is going to go smoothly. When you spend your weekends on the water, you start to appreciate the parts that make those easy starts possible. The Mercury Marine part number 862029 ACDelco MR43LTS Spark Plug is one of those small bu