>>>>>>>My ACI color #8 is 128,128,128.
>>>>>>>Does every release of autocad have it's own different ACI colors?

There is another thing - when you change display background color, AutoCAD adjusts RGB values for ACI colors 8, 9, 250, 251, 252, 253, 254 and 255 (grays) to ensure that lines of the corresponding color are visible on the screen.