39521 Bearing Cup Fits NTNOne New Aftermarket Replacement 39521 Bearing Cup for NTN Tapered Roller Bearings This aftermarket replacement 39521 bearing cup is the outer ring (cup race) of a single row tapered roller bearing in the inch series 39500 line. The cup pairs with a separately purchased cone (inner ring assembly) to form a complete tapered roller bearing capable of handling combined radial and axial loads. Common applications include axle systems, differentials,