I remember reading an article a while back in a magazine that Boeing are looking/evaluating a whole new rudder design that would be fitted to new builds and retrofitted to existing aircraft!!
Yes there is far more to this than meets the eye.
I won't say who I work for but our technical dept are already looking into the work that will be reqd to retrofit the 737 fleet !!
Do you have a note of the author/title or ISBN number of the book? As a 737 engineer I would love to get hold of a copy when released in the UK