Here is a little bigger diagram that Locdoc posted that shows the charging wires.
They join together in a soldered connection inside the harness behind the left headlight.
The circled fuses are for the battery gauge in the dash and the arrow points to the shunt wire that runs across the top of the radiator which carries battery current to the truck when the engine is off. It also carries current from the alternator battery voltage regulator junction back to the battery to charge it when it gets low.