driveshaft angles

Yeah, because you set it up with the rear axle upside down so you can get to the perches to weld them on, so you're actually pointing the pinion 5 down. Once flipped right side up and installed, the pinion has a 5 up angle built in.
So when you say you always set your rear ends with the front of the pinion pointing down toward the ground at a 5 degree angle relative to the ground this is with the rear end upside down?