Not 100% sure what your on about. There are
amendments to the book for changing the steering rack mounts on the chassis for the correct alignment. Which I think most people have done. After all why would you want the steering rack frame in a less than optimum position?
Also there are recommendations for shortening the sierra steering rack to fit, or using the escort MK 2 steering rack instead. Most opt for the escort steering rack, as standard. Although the book recommends the escort rack length is reduced to an precision length of 533mm between ball joints. I know of no one who has done this as it is nearly perfect anyway.
Hope this helps.