Michigan Motorsports 187 Degree Thermostat & Housing with ARP Bolts - Fits 1999-2006 LS1 LS2 LS6 Engines - 4.8L 5.3L 5.7L 6.0L - Replaces GM 12600172 (Black Bolts 134-7401)

Upgrade your LS engine’s cooling system with the Michigan Motorsports 187° Thermostat and Housing Kit, now bundled with premium ARP Thermostat Housing Bolts for a complete, high-strength installation. Designed to fit 1999–2006 LS-based engines including 4.8L, 5.3L, 5.7L, and 6.0L applications, this kit replaces GM part number 12600172 and maintains factory-spec temperature regulation. The thermostat opens at a precise 187°F to optimize engine performance and reduce the risk of overheating. The included billet housing offers OE-style fit and finish, while the ARP stainless bolts ensure superior clamping force, corrosion resistance, and torque consistency. Ideal for LS1, LS2, and LS6 engines, this combo is perfect for daily drivers, performance builds, or preventative maintenance.

• Complete Cooling System Upgrade Kit: This bundle includes a 187° thermostat, billet aluminum housing, and high-strength ARP thermostat housing bolts. It offers an all-in-one solution for refreshing your LS cooling system with both performance and durability in mind.
• Optimized Engine Temperature Control: Opening at 187°F, the thermostat maintains stable operating temps to prevent overheating, improve fuel efficiency, and reduce thermal cycling—critical for both stock and high-performance LS engine setups.
• High-Strength ARP Fasteners Included: ARP Stainless Steel or Black Finished bolts are designed to handle elevated heat and torque conditions. They resist galling and corrosion while maintaining torque specs better than stock hardware—ensuring a leak-free seal around the housing.
• Perfect Fit for 1999–2006 LS Engines: This assembly is a direct fit for LS1, LS2, and LS6 engines in 4.8L, 5.3L, 5.7L, and 6.0L configurations. It fits popular GM platforms like Silverado, Sierra, GTO, Camaro, Corvette, Tahoe, and Yukon without modification.
• Durable Materials & Long-Term Reliability: Constructed from brass and aluminum with stainless steel hardware, this kit provides long-lasting service in high-heat engine environments. Ideal for daily driving, towing, racing, or LS swaps.