your alternator could have a slightly low output, but sounds like things are OK, remember these gauges aren't high tech, just general indicators, you need to learn what's "normal" for your particular unit - the ammeter should show a definite discharge when the battery is low [like immediately after starting], then snap to at least a slight charge once the truck is running, and come back to around neutral after running a bit and the battery is back to full charge
Bill
