actually, they have replaced them with LARGER trucks - and have a BUNCH of smaller tradesman pickup type trucks. My neighbor (now retired) was an ESU cop.
You know their motto? When a person gets in trouble, they call a cop, when a cop gets in trouble, they call ESU
BTW ESU is NYC's equivilent to SWAT
BTW they have more than a smal rivalry with these guys
http://www.rescue5fdny.com/(I think there are 5 of each - FDNY and NYPD, plus there are Corrections, and the like, plus the command trucks from OEM, as well as each departments command trucks - I'ss see if I can dig up photos from a terrorist drill a couple of years back - 500+ pieces of equipment in one place - and remember, the city still had to run..