i put the big help plea here:
broken down on my wife... is this correct voltage???
but the short version is that I'm out of town, my wife is driving the truck and it lit the battery warning light and wouldn't start, just click.
sounds like a bad alternator to me, and according to the vin, it's a single alt system.
so i had a friend put a new alternator in and the voltages don't sound right for a healthy system:
12.8 at the battery at idle, 13 at the alternator at idle, rising a little when the engine revvs up, and reading 12.5 with the motor off.
i'm not looking forward to her driving it right now and i'm not going to be home for another week. ugh.
thanks so much for any help/ideas!