Changing the rear end over
How I set pinion angls.
http://www.rosslertrans.com/Pinion Angle.htm
It's one of the last thjngs that I do on a car. It's best done loaded on the suspension and at weight. Angle will depend on suspension style and use. Street car, try not to exceed 4* down.
On an A body rear, when installing the perches, factory set the angle of pinion is up 5* when perches are parallel to the ground. I NEVER install them there on my stuff. Most of the time I take most of that 5* angle out.