Rectangular port header gaskets for Chrysler LA-series small block engines, built with a high-temperature expanded-steel core for strength, stability, and dependable torque retention under severe exhaust heat. The graphite-impregnated facing conforms to minor flange irregularities, resists thermal breakdown, and helps draw heat away from the cylinder head for improved sealing longevity. High-recovery material maintains a tight seal even if the header flange loses clamp load, and the gasket can be trimmed to suit modified port configurations. Designed for OE replacement as well as high-performance street, drag race, and oval-track applications.