Davis Unified Ignition (D.U.I.) Dodge Big Block Distributors offer serious firepower and remains the most popular choice for hot rods, street cars, off-road vehicles and weekend race warriors! These distributors are the only one-piece ignition system for Dodge big block engines and have everything packed into one simple unit. No external coils or spark boxes are needed, just one 12 volt hot wire hook up sends 50,000 volts of pure spark energy to the plugs for a cleaner, crisper, more powerful running engine. A special weight and spring assembly is hand fitted and dialed-in for a precise timing curve that will match the specifications of your engine and vehicle. The super smooth advance provides instant throttle response and maximum power throughout the rpm range with no pre-detonation. Whether your engine is bone stock to highly modified, D.U.I.'s street/strip distributors deliver quality, reliability and performance that is unmatched. Due to size limitations, these distributors are not built with vacuum advance.