And what a lot of people forget is the side effects from 4e for a jarhead....
A jarhead that started life as a regular person had a 'life span" measured in weeks. (about 6 to 10) before the mental stress drove the brain to a psychotic break, leading to it killing everything around it, before itself...
(AKA: if you took a runner and got rid of the meat and just kept the head, 6 to 10 weeks before your mind is mush)
If they used a "fresh" brain (and this should disturb you), then the life span was measured in months (but still less then a year).
The key wording here is 'fresh', as in 'not aware of the human condition'....... (so.. figure that one out).
In essence, Jar-heads had less of a life span then Cyber-zombies. Which kinda makes sense as a jar-head has (generally speaking) much more extensive augmentations then a typical CZ (they ARE just a brain in a jar after all).
Rooks has the closest you can get until they re-release the jar-head stats again... but with CFD out there, and the state of nanotech, this MAY be something they gets left by the edition wayside....