Well, the letter "H" doesn't fit well with your HK unit, as that letter stands for humanoid within the original acronym. Even though H could be used for Hunter-killer, you'd still have "CHAS". You might then just add "MKII" to it and be done with it. Let's see what I might contribute for other options.
Hmm, how about...
V.E.R.A. (Vehicular Excursion, Robotic Assault), or
C.A.N.D.I. (Cybernetic Assault, Neural Directive Input)
[This means that it could interface with a human controller]
C.H.A.S.T.I.T.Y. (Cybernetic Hunter-killer Assault system, Tracked, w/ Independent Targeting Y-rack).
I like "Chastity". :wink:
"CHAS", then "CHASTITY". What do you think? Does it stick?
OK, back to CHAS MKII then. :lol: