Thermostat Housing -20 AN Mopar Style Polished

The Thermostat Housing -20 AN Mopar Style Polished from Billet Specialties is a precision-engineered water neck designed for serious Mopar V8 engine builders and high-performance cooling system upgrades. This component replaces the factory thermostat housing and serves as the critical junction where coolant flow is regulated and directed through your engine block. Whether you're building a restomod, upgrading cooling efficiency on a vintage or modern Mopar, or integrating custom coolant routing into a performance application, this polished aluminum housing provides both function and visual appeal under the hood.

Machined from lightweight aluminum and finished to a mirror-bright polish, the Thermostat Housing -20 AN Mopar Style accepts straight -20 AN male hose fittings, allowing seamless integration into braided stainless steel or custom coolant lines. The -20 AN port designation means it accommodates 1.25-inch hose diameters, providing excellent flow rates without restricting coolant circulation—critical for maintaining optimal engine temperature under load or high-RPM conditions. Billet Specialties includes stainless hardware throughout, ensuring corrosion resistance and reliable fastening in wet engine environments. The polished finish not only resists oxidation better than raw aluminum but also enhances aesthetics in show-quality builds and custom engine bays.

This thermostat housing is ideal for builders working on first-generation through modern Mopar V8 platforms who demand both performance and appearance. Custom coolant hose routing allows you to optimize flow paths, reduce hot spots, and integrate auxiliary cooling or overflow systems with confidence. Installation requires basic mechanical skills and standard hand tools; the compact 5.3 x 2.4 x 5.7-inch footprint fits tight engine compartments without interference. Verify your existing thermostat bore and hose configuration before ordering to ensure compatibility with your specific Mopar block and cooling system layout.