Performed annual heating maintenance granite bay. 29 yr split dedicated horizontal furnace attic. Went into hatch for down stairs unit, attic scattered with roofing debris. See pictures, used leaf blower to clear path so I could work. Multiple of the orginal grey duct work is starting to fall apart see pictures, outer barrier of duct work is ripping. Other portions of duct work have been replaced. Ran furnace, furnace operational at this time shows signs of thermal stress and rust. Some parts have been changed. Has newer hot surface ignitor. Upstairs unit, tight attic hatch in closet. newer with black ducts Due to age of systems and how inefficient they are recommend replacement.