The Rio Grande 5s just have something that stands out about them. The CB&Q 5 chimes are considered the best but I think the Rio Grande 5s are right up there with them.
It sounds close to 484's whistle in this video back in the 1980's just needs a little tweaking to be a tone lower ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-k3AqNi_gyTg.html