1978 K20 with a single 20gal tank. Should be an original-ish system with a quadrajet carb. Fuel lines were so old and brittle they cracked and I had fuel dripping everywhere. Dropped the tank to replace everything and I'm now looking for the piece on the center outlet. Plastic vent piece maybe....high pitch voice. I don't know what it is and am looking through parts sights without success.