difference between hydro and mechanical rocker shaft diameters

That's a good example of what I mean when I say the Mopar books are poorly written. Would it have been that tough for him to state "the stamped shafts were not ground; they were used 'as is' from the steel maker. Shafts used for bushed rockers received an extra grinding step to ensure roundness and to provide a finish compatible with the bushing material." ?