Problem with 77 f-250 w/ 429

Hi i have a 77 f-250 show truck with a 429 and i have an electrical problem where my lights just constantly pulsate. I have replaced the battery, alternator, ignition coil, brain box, solenoid but still no luck. I would GREATLY appreciate anyone out there that has any suggestions. I am getting very frustrated.

What exactly do you mean by pulsate? On and off, and the dim kinda? Check the grounds and take a volt meter and check the light connection. Sounds like a bad ground, so ground your volt meter to your battery and see if you have a varying voltage. if you don't, check all the grounding straps.