I haven't owned or played a New York but it's the add-a-ball to "Spirit of 76".
However, it has the same rule set as Spirit of 76 including the match feature
at the end of the game although the Replay unit is removed and the half-moon
replay window covered with stars. Also, both machines have a "Shoot Again" (not
that Shoot Again means add-a-ball), but outside of one being a Two Player and
the other a Four, anyone know what the difference is with the Add-a-Ball version
"New York" and the Replay version "Spirit of 76"?

I believe it stated that the Sample N.Y. machines had the Replay Units, but the Stars were added,
so it would seem the unit was unwired. Special for N.Y. probably lit "Same Player", but maybe
for S-76, Special could be converted to Same Player Shoots Again" or Replay.
Yes, it's not unusual for someone to hack the Replay Unit for added balls, but it's not anything I do.
All my multi-players have "Same Player Shoots" and I have them set on that, not Replay, so that's
good enough for me, however, I do have five true 2 Player Add-a-Ball machines that I'll have set up
someday, but since N.Y. isn't a true 2 Player AAB, and S76 also has a "Same Player Shoots Again", I'm
not sure what the difference is between the AAB N.Y., and Replay S76..
EDIT: My mistake. I checked back and yes, IPDB did state that the Replay Unit in the examples of
the N.Y. machines that they have seen were in the light box. When first reading, I took it as example
machines that they had seen..

I have add-a-balls, and a small stepper was used for 2/25c, and also, on New York, Gottlieb covered the Replay
window with stars, so I'm thinking maybe the Replay unit wasn't connected. Never playing a N.Y., I was wondering
what makes N.Y. an add-a-ball. The instruction card reads the exact same as Spirit of 76, and I imagine it reads the
same as Pioneer. Being from N.Y., I wouldn't mind picking up a N.Y. if it has a true add-a-ball feature, but so far
I don't see any difference on its game play than it's two cousins..

Yes, Replay machines in N.Y. State were always illegal because N.Y. state laws considered
winning free games as gambling. In 1960, (maybe 1959), Gottlieb convinced State law makers that
Add-a-Ball pinballs would not be gambling, but winning a free ball would be a form of achievement,
thus in 1960 came out Add-a-Ball for N.Y., Wisconsin, and Conneticut.
However, on multi-players, an adjustment for Replays or "Same Player Shoots Again" were on most
machines, thinking Pioneer or Spirit of 76 could be set to be legal. The Gottlieb multi-players I have from
that era has that option, and I have them set for"Shoot Again", not Replay..
But still, the question remains, I'm not aware why N.Y. is considered as an add-a-ball machine when
it appears it's rule set is exactly like Pioneer and Spirit of 76. The only difference is that N.Y. doesn't
give replays, but that alone wouldn't make it an add-a-ball machine. It has "Shoot Again". but so hasn't
the other two..