Description: All models. 4.3l. Silverado, sierra. 4.3l. Thick base helps prevent leaks by minimizing warpage Leak-resistant Neoprene O-ring seal Helps your cooling system function properly This GM Genuine Part is designed, engineered, and tested to rigorous standards and is backed by General Motors Original equipment parts are designed to work with your GM vehicle safety systems -- aftermarket replacement parts may not meet the same OE safety regulations, depending on the part type