I've only had a problem once when I was out in rural eastern Oregon on a late Saturday afternoon. It was getting desperate when I finally located an open station with diesel. I found out when my F-350 warns you it's low on fuel and says you are XX miles from empty it is not joking. When I filled it up I estimate that I had less than a gallon in the tank based on tank capacity.
On every gasser I've had there is always some reserve when the needle gets to empty, 5 gallons or so. Not on this truck.