Thanks for your reply. First to give some more info - my truck is a 1992 model. I don't know off-hand what the other details are: I bought it from my father-in-law's estate, and I don't have all the paperwork. The battery light comes on and stays on after the engine dies, but I figure this is normal for the situation where the ignition switch is "on" and the engine is not running.
I do have a problem (that I thought was not related, but your post makes me think twice) with the truck hesitating excessively when accelerating. I was going to change the fuel filter to try to remedy that - could it be the voltage regulator as well?
To be honest - I'd never heard of a thing called a voltage regulator - I'll have to read up on it...