Once again...I don't worry about the driveshaft angle unless the suspension is severely raised or lowered.
If the U-joints are close to binding (ie. lifted 4 x 4 truck), I alter the transmission centerline a few degrees to straighten out the driveshaft angle. I set the pinion parallel to the transmission, then I roll the pinion downward "X" degrees to acheive the desired "pinion angle".
