Sounds like you're talking about Traveller's old Psiberia and Psiberion character swap sets. With that you hide a body part and load and conform the replacement, creating as much cybernetic as you wanted. Question; did the figure have a replacement abdomen, where you had a mech spine and nothing else between ribs and pelvis? If so, then it was the traveller set, as that's the only one with that feature that I know of (and yes, the style is defintely in the T-800 look. Mostly. A bit more robust, though...) I don't think that one is for sale anymore, but you could sitemail traveller at rDNA and see what the status is