420 East 61st Street is the second part of the Sutton Place North towers. Tower One was constructed in the early 2000s, however the second tower became a victim of the credit crunch. Now developer, Sheldon Solow has decided to move forward with the tower.
There are no renderings that I know of, however the Tower Two will likely look much like Tower One (the black tower in the center of the photograph below):
Dick Johnson USA @ Flickr