The ultimate HEI kit has everything you need to make your early model GM HEI distributor a great performance distributor. The kit is supplied with MSD's digital heat module (PN 83647), MSD's GM HEI coil (PN 8225) pro billet HEI cap (PN 84111), and rotor (PN 84101). By using upgraded components, the heat produces high output for stock and MSD applications plus has a built-in rev limiter that is more accurate and easier to set with the engine running. MSD's heat digital HEI module is a direct plug-in for the 4-pin HEI module and will produce up to 8.5 A of current.