I don’t think these coaches had storage tanks , but with battery boxes there is a lot of confusion all of these coaches park royals , buffet cars and brakes had four battery boxes two on each side this was common practice, worlsey works supply them with only two battery boxes , I recently got a IFM TPO and this only has two as well when it should be four . I think the confusion comes from UK coaches normally having two but in Ireland particularly with CiE it is four or if its a TL coach then it’s no battery boxes .