[shifty]

Some questions:

Is there power at the voltage regulator where there should be? It is possible the voltage regulator took a crap on itself. It is mounted next to the horn on the driver's (in)side of the radiator support.

Start measuring the power from the battery -

Do you have power at the bulkhead next to the battery?
Do you have power at the voltage regulator?
Do you have ANY power on ANY lead in the fusebox?

The idea is simple troubleshooting: Find where the power stops.

You can use the diagram provided in the last post to know what wires should have power @ the regulator.

Also, have you looked at your ignition switch as well to make sure nobody tried to hotwire the truck and left some lines off or something?