I believe the book was giving an example with the transmission at 0* to make it simple to understand. They are telling you that "wherever" the transmission "is" the pinion should be 3-4* down "from that". .......just like everyone has told you all along.
I understand what people have been saying, it's just that i have read so many articles on this and got mixed opinions. Now that i understand mopar is a different animal i can try what others have been saying, down with the rear angle.