As Kevin said they were built with hoots, but over the years, they got 3 chimes and/or 5 chimes. One have to study pics of individual engines to get the corrct answer. 452 has a hoot at the end, 453 a 5 chime, 463 had a hoot for about the 75 years, 461 had a 5 chime on the RGS, but before it had a hoot. My guess is when the engine got shopped and if the whistle leaked, it got changed for something else. But there were those out there the wanted a local engine to have the right sound and put something else on it.