T.I. Voltage Regulator Adapter Harness - Used on the 1965 small block L75, with transistor ignition, without A/C, this harness is used to filter-out ignition noise caused from the engine harness. Without this Adapter Harness, noise induced into the T.I. harness from the Engine Harness could cause your engine to misfire. This harness contains a noise canceling diode. The actual application of this harness is vague. No documentation is available as to whether it is used on a big block, small blockor both.
Electrical components such as a harness are non-returnable parts.
Always refer to a factory service manual when diagnosing engine service problems. You can damage electrical components if the proper procedures are not followed. Be sure you are replacing the correct part.