To upgrade a 12SI alternator (’80s Monte Carlos and Camaros), the CS130 is a good swap. The 12SI alternator has two leads. Lead 1 goes to the indicator light, while the No. 2 connector is a voltage-sensing wire. The CS130 alternator uses four connections—marked either PLFS or PLI/FS. In either case, using a stock connector, connect the L to either the charge indicator light from under the dash or to a switched 12-volt wire, using a 50- to 100-ohm resistor from Radio Shack.