Charging system trouble Any ideas?

[Truck Hippy]

I have a 72' swb 4x4 with the 350/auto. The alt. went out so I go to Advance auto parts and get a new one. Bolt it on and it stops running when I take the cable off the battery. I put a new voltage reg. on it and its fine............ for a few days. I go to the beer store one day just before dark. I turn on the head lights and they are so bright I think there going to melt the guy in front of me back window. The faster I go the brighter the lights. I figure I got a bad reg. I put a used one on and its fine...........for a few days. Same thing happens. The head lights are so bright is like looking at the sun. Advance say the new alt. is working fine. Any ideas? Thanks, Wes.