No front gas tank in Ford F-250

I was wondering why my 96 f250 only has
a rear gas tank? There’s no door, no tunnel
in the bed for the neck, nothing. There’s an
open space under the truck like one would
fit but there’s no sign of there ever being
one. I was just wondering if someone else
has another f250 like this. I’ve never seen
one like this. There’s not even a switch in
the cab to switch it back and forth.
Nothing.