9S7079 Muffler Fits Caterpillar C7One New Aftermarket Replacement Muffler for Caterpillar (Cat) Industrial Engines and Construction Equipment This aftermarket replacement muffler fits Caterpillar C7, 3126B, and SPP101 engines used in a range of industrial, petroleum, and construction applications, including the 627 and 637 scraper series. The muffler routes and reduces exhaust noise from the engine's exhaust system, keeping equipment operating within acceptable sound levels.