Dan,
You're looking for a metal box that has a large plug on the bottom with 4 wires going into it. It'll be on the driver's side of the radiator. Autozone sells one, Wells VR715,
http://www2.autozone.com/servlet/UiBroker?UseCase=C001&UserAction=performMoreDetail&Parameters=TRUE%7C%7EVOLTAGE+REGULATOR%7C%7ENONE%7C%7EWELLS%7C%7ENONE%7C%7EFALSE%7C%7EFALSE%7C%7 E130005%7C%7E1860%7C%7EVR715%7C%7ETO+TEST-%3E+LOCATE+PART+NUMBER+IN+WELLS+TEST+MANUAL%7C%7E%2411.49%7C%7ECHEVROLET%7C%7ECHEVELLE%7C%7E1971%7C%7E3+MO%7C%7E0.4%7C%7EEA%7C%7EB
You're looking for a metal box that has a large plug on the bottom with 4 wires going into it. It'll be on the driver's side of the radiator. Autozone sells one, Wells VR715,
http://www2.autozone.com/servlet/UiBroker?UseCase=C001&UserAction=performMoreDetail&Parameters=TRUE%7C%7EVOLTAGE+REGULATOR%7C%7ENONE%7C%7EWELLS%7C%7ENONE%7C%7EFALSE%7C%7EFALSE%7C%7 E130005%7C%7E1860%7C%7EVR715%7C%7ETO+TEST-%3E+LOCATE+PART+NUMBER+IN+WELLS+TEST+MANUAL%7C%7E%2411.49%7C%7ECHEVROLET%7C%7ECHEVELLE%7C%7E1971%7C%7E3+MO%7C%7E0.4%7C%7EEA%7C%7EB