Best 904/A500 book

Three

The one listed above, the factory shop manual, and the book by Munroe. Not necessarily buy it here, just showing you waht it is
Torqueflite A-727 Transmission Handbook HP1399 by Carl Munroe: 9781557883995 | PenguinRandomHouse.com: Books

Also, there's some pretty good videos on the www, more 727 based, but a lot of that is applicable

Video reference, TF727 600hp rebuild