4W5488 Standard Bearing Fits CaterpillarOne New Aftermarket Replacement Standard Main Bearing Fits Caterpillar (Fits CAT) Industrial and Construction Equipment This standard (STD) size crankshaft main bearing is a direct fit aftermarket replacement Fits Caterpillar (Fits CAT) engines. Main bearings support the crankshaft within the engine block, maintaining proper crankshaft alignment and oil film clearances critical to engine longevity and performance. Verify your engine model and