Charlie
The fuel tank holds 90 Gal. You can download the Brochure and Spec Sheet here,
National RV Archives sorry I sent you the ones for the 1999.
That little white thing on the wall in the shower room is the temp sensor for the rear furnace. Your thermostat controls two zones. Zone 1 is the forward furnace located under the Fridge, and zone two is the rear furnace under the bathroom sink. To switch between zones on the thermostat press the top two buttons at the same time and the display will indicate which one your setting. Don't cover up the little white thing on the wall or the rear furnace won't know when to turn on or off.
Dick