https://en.wikipedia.org/wiki/Hancock_air_whistle in the Users section says this:

The New York, New Haven and Hartford Railroad was the largest user of these whistles, and every FL9 purchased by the New Haven came from the factory equipped with a Hancock 4700 air whistle on the roof in the front, and an H4700 whistle (no reflector dish) on the rear. Additionally, the NH’s 40 Budd RDCs had two Hancock 4700 whistles, plus their Mack FCD-1 & FCD-2 railbuses, 30 GP9s, 15 RS-11s, 15 H-16-44s, 20 SW1200s & their fleet of Pullman-Westinghouse stainless steel MUs. One DL-109 was also retrofitted with a pair.

The DL-109 that was retrofitted with a pair of Hancock Whistles was The Cranberry.