Brad,
Basically there are three choices for power. If the choice is to have the panel and all it's accessories shut off when you turn the key OFF and leave the truck, then it must get power through the key switch.
If that isn't important to you, then it can be tapped off the - side of the ammeter or even of the starter switch itself...or even the battery. Just make sure you fuse the power feed to the panel properly.
A third choice would be to power it through a husky relay that was controlled by the ignition switch. This way all accessories would shut down when you left the truck and the key switch wouldn't take a hit on passing all the current for the new panel, only the small relay.
Stuart
