These fellows are the servitors for my Guard army's two Enginseers.  They each have two HB servitors and two Tech servitors each - if you're ever going to deploy an Enginseer, he needs all the help you can give him.
 They sat half done for years and you may have seen them on the table with grey undercoat skin and boots.  Indeed, I did want them to have sort of sallow and greyish skin anyway, but these guys have ended up with 'normal' skin (as I do it...)  Which perhaps actually makes these servitors (lobotomised cyborgs) perhaps a bit more creepy.
The dark patches on them are fenris grey (which is prussian blue [?]) over their shadow grey jump suits; this is supposed to be wet patches; biological fluids or mineral oils seeping out of them.  It looks ok in the flesh. 

 There is a bit in the Word Bearer's omnibus where the Ad Mech persuades the Iggy general that dead and dying guardsmen could be buried with honour, but that they could continue to serve if they were handed over to the Ad Mech as a resource.
 "Only in death does duty end."  So, if like the Dread Pirate Roberts you happen to find yourself 'mostly dead' whilst in the Imperial Guard, then you may well end up as a servitor.
 Fluftastically, the armies on Devos IV are led by a coterie of Vostroyans, who have strong ties with the Ad Mech, so if your named character gets wounded on Devos IV, watch out...
All eight of them.  Basing in the future, when whole loads of people will be based at once.