Rust is the enemy of your coolant system. Upgrade your rusty OEM thermostat housing cover with a Cast 304 Stainless Steel Thermostat Housing Cover from PPE. This direct bolt-on replacement adds style and function to your engine bay. The stainless steel material is corrosion and rust resistant. We've engineered an easy way of bleeding off air from your coolant system by adding our Black Anodized Aluminum Bleeder Screw with a built-in air channel and a Viton O-ring. This makes quick work of purging air from your system without removing the entire screw. Just turn, purge and tighten. 2001-2004 GM 6.6L Duramax Thermostat Housing Cover Raw