See the discussion and my pictures in this thread.
It's a 8 1/4 but I think the idea is the same for angle and centering measurment
Use the car as a "jig".
Make the axel centered in the car and the pinon will be where it is supposed to be.
I figure. http://www.forabodiesonly.com/mopar/showthread.php?t=39098&highlight=rear+end
