Flickering or pulstating Headlights

Could also be a regulator or the regulator ground (scrape the paint on the firewall where the bolts go through). Could also be the alternator brushes. Try disconnecting the wire on the alternator and ground the brush connection. This will make the alternator go to full charge. Try revving the engine and see if it still flickers. If it does then I would suspect the alternator. If it doesn't then I would checked (as mentioned above) the ground on the regulator and possibly the regulator itself. If all else fails try jumping battery voltage to the "I" (ignition) terminal on the regulator. This is a test that mimics the relay mod. If it works then install the relay. I am here to help if you have questions.