MECHMAN 71-30062 USI GM 4 PIN
 

This is a simple pigtail that plugs into any oval shaped 4 pin GM alternator plug. The blue wire gets looped onto the alternator output stud (battery positive) connection while the yellow wire gets connected to any ignition switched 12 volts. This is a great way to easily wire multiple GM alternators onto a vehicle, or adapt a GM alternator on to a different vehicle.