Upgrade your classic Chevrolet's performance and electrical reliability with the GM 1966 Fullsize Engine Harness. Designed specifically for 396 and 427 cubic inch (C.I.) engines, this premium-quality harness ensures a seamless connection throughout your vehicle's electrical system. With built-in warning lights and compatibility with factory air conditioning (C.A.C.), it's the perfect replacement for outdated or damaged wiring, far surpassing alternatives in quality and durability.