I have a new 2020 Ram 2500 6ft 4 bed. I can't seem to find a part number or a place to order the bed rail system. I see them for the 8ft bed but not mine. 2) I have the Harmon Kardon sound system and it is supposed to come with active noise cancellation. I don't think it is working and the dealer said they don't know how to test it. Any idea of how to see if it is working correctly?