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