Sikorsky had to completely redesign the tail and lengthen the forward fuselage 41cm. Wiki says that the latter was "In response to requests for additional cabin space". Actually it was to move the c/g forward.
The early-configuration prototype S-92 (bottom in Hesham's Flight image) pitched-up at 60 kts (110 km/h). The tail redesign was to address the same problem. The Stallion-ish tail (high-mounted horizontal, strut-braced) was moved down and switched sides. The vertical fin was shortened, lowering the tail rotor position.
Here is photo of actual S-92 Prototype aircraft that was modified. Area where fuselage was extended can be seen at left of photo. I took this photo while going through the pilot training course to get S-92 type rating.