Total loss of electrical

[kcsa75]

So after work I start my truck (72 C-10, 350/350). When I turned on the lights, the needle on the tach went to zero momentarily and the light on the radio flashed. I turned the lights off and back on again a couple more times and the same thing happened. Then I put it in reverse, went about three feet and everything died. There was no juice anywhere. Zip, Zilch, Nadda, Nothin.

I looked under the hood and didn't see anything obvious. So I tapped on the voltage regulator and the alternator with my flashlight. I got back in, started right up, and I drove home without a problem. All the presets on the radio were gone, which means it lost all power.

My only thought is the regulator is going bad. But I know about as much about electrical as I do nuclear physics.

Any help would be appreciated.