On various fora I've been asked about the parts used for the Murder servitors, so I thinks it's time for a full listing. Links to most suppliers can be found in the right sidebar.
All of them have; GW Ghoul body and legs, Anvilindustry leg guards/armour, head from puppetswar, and various bits of plasticprofiles - the spine-plugs are simply 1mm rod drilled into the back. Cables are either thin guitar-wire, or home-made using Procreate and a tubetool.
Mk 1: GW Cronos pain-engine arm and vial, Necron spine, Kroot shoulderpad, IG optic, Ghoul arm
Mk 2: Anvilindustry bionicarms and chain bayonets.
Mk 3: Ghoul arms with guitar-wire, Kroot shoulderpads, Cronos pain-engine vial and syringe.
Mk 4: GW Cronos pain-engine arms, Necron gun power cell.
Mk 5: Anvilindustry bionicarms and chain bayonets, Necron spine