Wiring Harness Adapter This is used on some models that came with a 4 terminal plug on the regulator and an extra black cube(appx 0.75" x 1") mounted beside the voltage regulator. The contents of the black cube are now inside the new regulators and you must use the harness to use this new style regulator(old style regulator is no longer sold). If you already have a 6 plug harness on your regulator you will NOT need the adapter harness. .
Regulator replaces many models such as the RS5101 & RS5102
121522-77790 RS5101 & RS5102 121522-77790 , 121450-77790 , 121450-77711 , 121520-77710 , 121450-77710