Crank the truck, stick a screwdriver to the rear of the alternator just where the rear bearing is, careful not to touch anything else, and if it sticks the alternator is charging. If it doesnt stick, its not charging. Replace the Voltage regulator. Your external regulator may be what burned up the alternator to begin with. You should always replace the regulator when replacing the alternator, otherwise you run the risk of the same thing happening.
Ken
www.classicgenerator.com
