Designed to meet the high performance demands of racing competition, these units fit Chevy small block and big block engines. These 100% NEW distributors have all the reliable components of the 66940, but they also include a highpower 50,000 volt coil. This high-performance distributor produces a 50,000 volt spark through 7,500 RPM with true spark alignment for instantaneous response, a high performance curve, a premium cap with brass terminals, and a low-saturation ignition module. All have die-cast aluminum housings, polished to a brilliant billet-look appearance, except as noted. NOTE: without vacuum advance: uses nylon lock-out.