Pinion angle and diff centering

I would turn the driveshaft till one of the driveshaft ujoints is at 6 o'clock & take a reading on the cap itself then turn the driveshaft 1/4 turn till one of the pinion ujoints is at 6 o'clock & take another reading at the cap itself. you want the difference between the two numbers to be at least .5 degree but not more than 3 degrees but less is better & 2 degrees to .5 degrees is acceptable and then turn the front ujoint till the cap is at 6 o'clock & take a measurement then turn the driveshaft 1/4 turn till the transmission ujoint cap is at 6 o'clock & take a measurement. same as before you want the difference between em to be at least .5 degrees not more than 3 degrees & 2 or less is ideal & when done you want the 2 angles front and rear to be no more than 1 degree different from each other. now looking at this from the side of the car are the angles at the (front driveshaft/transmission ujoints) "up" or "down" and is the triangle of the driveshaft/pinion ujoints pointing "up" or "down" & you want one of these triangles to be "up" & the other "down" & you would shim the trans mount up or mill it down and or rotate the housing before you weld it to achieve that. However in the vid he states that these specs are for coil spring cars & leaf spring specs are different (I'm looking for em). just my OCD!