I have been using the 1J version and found it useful. Particularly pointing out things like where the double set screws are and such. It's written a bit like the Chilton car repair manuals. I've found it worth the $30.
I used it when rebuilding everything above the spindle on my variable speed Bridgeport. New bearings, varidiscs, bull gears, etc. Lots of good pictures to go along with the text. I thought it was well worth the money.