Fits Caterpillar 9L5521 MANIFOLD NEWOne New Aftermarket Replacement Rear Exhaust Manifold Fits Caterpillar (Fits CAT) 3306 Engine This aftermarket replacement rear exhaust manifold (end section) is designed for use with the Fits Caterpillar 3306, 3306B, and 3306C diesel engines. The Fits Caterpillar 3306 uses a 3 piece exhaust manifold assembly; part number 9L5521 is the rear end section of that assembly. It collects exhaust gases from the rear cylinders and directs them into the