8S3970 Chamber Assy Fits Caterpillar 8S3990, 9S8679, 2423438, 3256042, 8S-3970One New Aftermarket Replacement Pre Combustion Chamber Assembly Fits Caterpillar (Fits CAT) 3304 and 3306 Engines This aftermarket replacement pre combustion chamber assembly (Chamber A) Fits Caterpillar 3304 and 3306 diesel engines used across a wide range of Fits CAT construction and industrial equipment. The precombustion chamber is the space in the cylinder head where fuel is initially ignited before combustion spreads to the main cylinder, making