Some non-authoritative word:
The 53X will have an S-92 type rotor head, with the same basic design (redundant wrap-around arms and flaw tolerance) as well as S-92 type blades (advanced airfoils and full composite design).
The engines will be significantly higher in power (6,000+ HP vice today's 4300 HP) to give the aircraft much more hot/high performance. The transmission will be somewhat upgraded from today's, but of the same basic design.