In modern times, there has always only been the one bearing width of .842 as the recognized standard for all the 6's and 8's made by the more premium top shelf brands, could have been a misprint or outdated source of info you found that indicated otherwise. Some generic brands might have offered something different if there was a different width.
Older books are neat as a reference, but often are found to be irrelevant on some issues pertinent in todays mainstream, as many companies update and change procedures with time and advances in technology requires them to, and many parts are superceded or replaced by newer designs and thinking.
