Wehrli 100155 Billet Coolant Heater Core Firewall Fitting | 1999-2025 GM Silverado/Sierra 2500HD/3500HD 6.6L Duramax

Features: - Replaces failure-prone factory plastic fitting - Billet aluminum construction for durability - 5/8" hose barb connection - Double O-ring seal prevents leaks - Clear anodized finish resists corrosion - Direct-fit upgrade, no modifications needed - Withstands heat and engine vibration - Made in the USA - Compatible with GM Part 15032062 - Also replaces Dorman 800-409 - Improves long-term reliability - Quick and easy installation Add More Durability and Relibiality to your GM Duramax Engine If you’ve ever dealt with a cracked or leaking plastic coolant fitting, you know how frustrating it can be. The factory heater core firewall fitting on Duramax-equipped GM trucks is a known weak point, and over time, heat and vibration take their toll. That’s where this billet aluminum upgrade from Wehrli Custom Fabrication comes in. Built as a direct replacement for the OEM part, this fitting is machined from high-quality aluminum and designed to hold up far better than the stock plastic piece. It features a 5/8" hose barb and double O-ring seal to help eliminate leaks, even under long-term heat cycles and engine vibration. The clear anodized finish adds corrosion resistance, giving it a clean, long-lasting appearance that’s built to handle the elements. Simple Install Installation is straightforward and doesn’t require any special tools or permanent modifications. Whether you’re doing preventative maintenance or replacing a fitting that’s already failed, this is a simple upgrade that brings real peace of mind. It fits a wide range of GM trucks from 1999 to 2025, including both Silverado and Sierra 2500HD/3500HD models. Fits: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 GM Sierra/Silverado 2500HD/3500HD 6.6L Duramax Notes: - Direct replacement for failure-prone factory plastic fitting - Compatible with GM Part #15032062 and Dorman #800-409 - Fits 1999–2025 GM Silverado and Sierra 2500HD/3500HD - Machined from billet aluminum for long-term durability - 5/8" hose barb with double O-ring for secure seal - Clear anodized finish resists corrosion and wear - Designed to withstand engine heat and vibration - Ideal for preventative maintenance or failed part replacement - No special tools or modifications required for install - Made in the USA with high-quality materials - Helps prevent coolant leaks and improves reliability - Clean appearance and long-lasting performance under the hood