2299601 Muffler As Fits Caterpillar ModelsOne New Aftermarket Replacement Muffler Assembly for Caterpillar (Cat) Track Type Tractors This aftermarket replacement muffler assembly (Muffler As) fits Caterpillar track type dozers including the D6R, D6T, and D7R series. The muffler is part of the engine exhaust system and functions to reduce exhaust noise and manage exhaust gas flow for quieter, efficient operation. It is a direct fit replacement for the original Cat 229 9601 muffler assembly.