The Motorized Servo actuation system in everything, aside from the hands and ankles, have been replaced with some form of system either synthetic muscle or hydraulic in principle, to eliminate the sound of servo actuation.
The standard metal external plating has been replaced with sensor-absorptive, ablative polymer and ceramic plates, with some metal underneath them to retain protection from at least small arms.
The Internals remain strikingly similar, the only difference between them and those of a standard ZAKU II is streamlining of the systems, circuitry and chasis.
- Cursory findings on Captured ZAKU II Stealth.
(note, I wrote this out once, But accidentally deleted it!)