GM 6.6L Duramax Coolant Bypass Tube - LMLThe OEM mild steel tube is prone to rust, which can lead to coolant system contamination and eventual leaks. Over time, factory O-rings also tend to harden and lose compression, increasing the risk of failure. PPE's upgraded bypass tube is specifically designed to work with the factory water pump and is crafted from high-grade 304 stainless to prevent corrosion and ensure reliable, long-term performance.