This harness is manufactured according to the original General Motors specifications. Each harness is fully assembled taped and ready to install upon arrival. This harness will plug into the firewall in the factory location and follow the original routing in the engine compartment. A combination of the engine and front light harness accomplishes most functions under the hood of an early GM vehicle. Engine harness design varied significantly from year to year but most will contain wiring for the ignition system starter heater blower and temperature/oil pressure sender wires if applicable. Some vehicles used a capillary tube to provide an oil pressure reading so these will not be included in a wiring harness. On vehicles with ignition points the circuit feeding the ignition coil was designed with some resistance to extend the life of the ignition point set. Modern electronic ignition systems or high-energy ignition (HEI) systems do not require resistance in the circuit so it is recommended that a harness modified for HEI be ordered if the ignition system has been upgraded. In most cases these harnesses are available in our catalog and feature unique part numbers. NOTE: Image of product is for reference only and may not be cosmetically correct for the application.