If you look at your wiring system you are providing power to everything. But just as important is the ground [-]. Are you providing a good ground to everything? The headlights require more power than just about everything else except for the starter. If you have a ground issue the headlights will tax it.

It is a good thing you only have a two headlight system, with a 4 headlight system if you were to put on the high beam you would either burn something out or the headlights would be even dimmer.

Edit: The other problem with dim headlights is voltage loss going thru the bulkhead, light switch, foot switch, bulkhead again, and finally the headlights. Voltage checks will verify where your losses are.

Allen Here's a novel idea, let's not throw a bunch of parts at the car hoping it will fix the problem and instead spend a little time diagnosing it first. Life was a little easier when I was just a wrench.