Need basic help removing Suburban Furnace

[Burgermeister]

The "notable quote" for "intelligent" approach to fixing things is:

"There's no problem so great or difficult that it cannot be resolved by brute strength and ignorance alone!"

[Hartley]

In the picture that you show, The factory intake and exhaust tubes have been modified using car exhaust pipe extensions
that are flared to slip over the tubes on the end of the furnace. The exterior shot shows that someone may have just
jammed the pieces on there and not used the original mounting screws. The Long one that should be in the exhaust tube
center is missing and that is broken out. That screw normally is only about 4 inches long and would not have reached anyway
with the extender tubes anyway.

Tap on the tubes lightly at the back of the furnace to see if they will loosen up and then pry the cover off from outside. Plan on getting a new cover as that one is trashed anyway. I would guess that moisture and rust has welded the inside of the extended tubes to the tubes on the burner assembly.

Good luck......