I'm not belittling the wealth of information available from the experienced mechanics on this site related to pinion angle, but I found it to be a little overwhelming. Admittedly, I was confused by some of it and I set up my pinion angle on an 8-3/4 swap wrong on the first try. After consulting with a very friendly driveline shop, I made changes and found success. You'll see the explanation in the diagram attached. Please excuse the artwork. 
