Eliminate unnecessary transmission fluid cooling delays on your 2017–2019 Chevrolet Silverado HD or GMC Sierra HD with the Wehrli Custom Fabrication Billet Anodized Transmission Cooler Thermostat Bypass Plug for the 6.6L L5P Duramax. This precision-machined billet aluminum plug replaces the factory transmission cooler thermostat, allowing transmission fluid to flow directly through the cooler at all times — reducing transmission temperatures under towing, competition, and heavy-use driving conditions.
Wehrli CNC-machines this bypass plug to exact OEM thread specifications for a direct, leak-free installation that takes just minutes. The anodized aluminum finish provides excellent corrosion resistance and adds a finished, custom appearance. An ideal modification for performance-oriented L5P Duramax owners who want to keep transmission temps in check.
Key Features
- Fits: 2017–2019 Chevrolet Silverado 2500HD / 3500HD and GMC Sierra 2500HD / 3500HD with 6.6L L5P Duramax diesel
- Billet aluminum transmission cooler thermostat bypass plug
- Allows constant fluid flow through transmission cooler — reduces transmission operating temps
- CNC-machined to OEM thread specs — direct, no-modification install
- Anodized aluminum finish — corrosion-resistant and aesthetically clean
- Ideal for towing, performance, and high-load applications
- Made in the USA by Wehrli Custom Fabrication (WCFab)
- MPN: WCF100469
A simple but effective modification for any hard-working or performance L5P Duramax. Lower transmission temps mean greater longevity and better performance under demanding conditions. Pairs well with upgraded transmission coolers and other drivetrain cooling improvements.