Voltage regulator is a black box on the firewall somwhere by the AC... it will have a Capacitor comming off of it on the right. Has a harness that plugs into the bottom (can't rember how many wires.. sorry).
I searched another Buick site & found that volt. output should be 15.5-18 max.
I don't see how that would cause a no start issue though... If the alt is putting out more than enough voltage..... Unless its frying the battery maybe. I don't know. Have you had any of the batteries checked after the problem happened. Disc. auto or Autozone will load test them for nothing.
http://www.v8buick.com/showthread.ph...tage+regulator
Scroll down to the pic... Box on the firewall just behind the air cleaner is the Volt. regulator.
I don't seem to be able to post pic's here... so just follow the link.
Good Luck.
EDIT...
Found another link to Volt. Reg. issues....
http://www.v8buick.com/showthread.php?t=59281