Stooby,
I see you are located
across the pond and may not have easy access to a "Shop Manual".
If you need the shop manual info sooner, and don't mind viewing/reading on your computer, this is a freely accessible web link to the the
1955 2nd Series Shop Manual that covers your 1956 steering box checks and adjustments (and everything else on your truck).
For the direct link to the section you need,
click HERE.
Once you have given this a read, come back and ask more questions if you need more info.
Dan
