Hi BDP,
The NKP 765 group has a number of whistles in the collection and they occasionally swap them out on the 765. Not sure how many they own, but enough of them thats for sure. Two whistles on the 765 is the norm for as long as I can remember. (1979 to present) If I am remembering correctly the N&W "hooter" that was used on the 1218 was on loan from the NKP group during it's excursion days. The "hooter" whistle was used a lot on the 765 in the early 1980's.