Our heavy duty replacement front wiring system for the "King" D21! New upgraded circuitry & components make up this nice system.  This system is designed for the OEM Delco "DN" series Alternator & external Voltage Regulator that originally came on the D21. All new upgraded 56 series flat Delphi plugs and terminals, replaces the OEM Molex pin type connectors that Mother Nature played havoc with. One gauge heavier wire throughout the system gets rid of the low voltage problem throughout the system. Shrink tube connectors make this one bullet proof wiring system for the "King" of AC Tractors. Soldered joints makes this a high vibration proof system for hard working Diesel engines. Don't guess. Get the best from B&B Custom Circuits!!