GM 4.3 Marine Engines ATK is a leading manufacturer of marine engines that are made with maximum performance and long term durability in mind. The engines are designed and built specifically for boating and all the rigors and conditions marine engines face. ATK takes pride in the fact that there are over 150 processes involved in remanufacturing each ATK engine including the GM 4.3 Marine Engine. Your boat is only as good as the engine in it. Without an engine in good working order, you might as