Yes, the Signal Stat beacon with the extension base was used by NYPD just on its 1972 cars (well, plus at least some of its 1971 Highway Patrol cars). Very hard to find; few other customers used them. At the time Dietz also offered a similar extension base (to go under their 211 / 7-11 beacon) in at least a couple of different heights, but the Dietz version had a lip around the bottom; again few customers bought it.
Why the switch? Various theories. Low bid? NYPD was experimenting with alternative equipment in '71 & '72. Signal Stat may have been deemed as a local (Brooklyn) NYC vendor. Note that the following year, 1973, all of NYPD's new warning equipment became Signal Stat rather than FS, so this may have been Signal Stat's "foot in the door."