Who ever put the rollback on this truck that I just purchased cut alot of wires off on the frame rail.I need a wiring diagram for the sending unit.I have all the other wires figured out and have a few dead wires it seems too.I do not see the matching colors of wires on the sending unit to wires that are on the frame rail...My fuel guage reads full all the time.How does it work?Does that mean someone hooked up a permanent ground or posative to it to make it read full? both wires that go to the sending unit should read ground correct?

Again 99 f550 super duty 7.3 turbo diesel.
Thanks.