Hexagon Flange Nut 3903210 covers a wide range of Cummins engines, including B3.3, B3.9, 6B5.9, 6C8.3, F3.8, ISB, B4.5, B6.7, ISC8.3, ISL8.9, ISX11.9, ISX12, ISX15, K19, K50, and ISZ13. It provides a strong, stable fastening with a built-in flange for better load distribution. OEM quality for a secure fit.