The 2003 Ford F-350's transfer case oil type depends on the specific transfer case installed. Ford used several different transfer cases in that year and model.
You MUST check your owner's manual or the sticker located on the transfer case itself to determine the correct fluid.
The owner's manual will specify the exact type and amount of fluid required. Trying to use the wrong fluid can severely damage your transfer case.
Don't rely on general advice online; always consult your vehicle's documentation for this critical information.
