I'm not familiar with your particular unit. Their location can vary. Not useful to the model number issue, but if you don't have an owner's manual, here's a generic one for an '02:
https://keystone-rv-dealer-app.cdn.p...al-revised.pdf
Most trailers come with a large binder with manuals for the various appliances and systems made by other manufacturer's. You might be able to find your specific furnace model if you have that binder.
A walk-around of the trailer should reveal two places that exhaust hot gas. One for the water heater and one for the furnace. You might find a model number behind the outside cover, or on the inside. Some manufacturers place the intake under the oven - just depends.