The exhaust port on the outside of your old Cobra will not look like the one in the picture that robsouth posted. It will be a plate will two 1.5 inch holes in it one of them a inch above the other.
Your furnace will just be a big tin box mounteunderneathhe something.You will not be able to see it without removing a panel. That panel will most likely be a wire mesh looking screen. The reason for that is that the cold air is drawn through the screen, heated by the furnace, and then forced out through the ducts. Quite often these furnaces werunderneathhe the fridge but, it doesn't have to be. But, it's mounted anywherunderneathhsomethingng.
Now, with that being said. There were smaller campers where the furnace was different.It coveredverd by a big tin cover and the cold air, and heated air went in and came out of the same cover. But, if you had one of them you probley have found it by now.
Tell, us what you find first, then gives us the name and any numbers you find that are printed on it. After that all the members here wiablee abel to help you better.