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While there may be a Winnibago specific manual out there, it would not cover items that are not Winnibago. For example: refrigerator, air conditionner, television, radio, furnace, water heater, ...
You would need to go to the manufacturer of these items for the manual.
Perhaps - give Winnebago Owner Relations a call. If they can't get the entire document into your hands, they might be able to copy any areas of interest for you.