Quote: Pinion angle is the relationship between the pinion centerline and the transmission centerline. It is not relative to the ground nor to the angle of the driveshaft.
Ideally, you want the pinion to become parallel to the transmission under a load, so you point the pinion downward a few degrees when the vehicle is resting on its suspension to compensate for pinion wind-up.
In other words, make the pinion parallel to the transmission as a base line, then roll the pinion downward 2-4 degrees and weld the perches. This is how a 2 joint driveshaft is designed to work.
What he said^^^^ you want opposing u joint angles under full power so if the trans is 2 degrees down you want the diff 2 degrees up under load.
