The GT stood for General Technical, when I took it in June of 1980 the
max score was 136, mine was 133. Over the years and depending what MOS`s
needed to be filled the scores were altered to fit the needs of the
service. In Oct, 1980 they were more or less standardized.
It actually changes (as far as I've heard) depending on what jobs need filled. It lets the higher ups adjust scores without adjusting standards...or so goes the argument. When I joined I got a 133 GT with a max of 136 possible. I have since met a new private with a GT of 145(ish), if I remember correctly he was told the max was 150.