After puzzling for several trips why my fuel gauge showed nearly empty but I could only add 65 gallons to my 105 gallon tank; and after calling Gillig only to be told "it sounds like a bad sender", I pulled the side mounted sender to check. First Gillig said I would have to drop the tank - wrong - the sender is side mounted and comes right out. Then to check it I measured the resistance and found it was 3 to 90 ohms. The problem is the gauge installed by Barth requires a 3 to 240 ohm sender. I have checked and found the Gillig Phantom Bus, on which the Barth 93 chassis was built used 24 volt systems while Barth installed 12 volt systems. So puzzle is solved - I am getting the sender rebuilt to be a 3 to 240 ohm unit and will then reinstall. Anyone else with a Gillig, about 1993 (or based on the Phantom Chassis) and who has a similar problem can check the sender by removing the 5 nuts and pulling it out. On the inside you will find etched on the mount 90 Ohms.