As much as King annoys me (lol) from time to time with his posts, he is absolutely correct.
However, the process is actually fairly easy. Once the gearbox is mounted to the engine, put the driveshaft in and bolt it to the diff and use a jack to get all the drivetrain angles. Just use a $30 digital angle finder from HF and you are good to go (unless you want to use a protractor......)
Ideally it should all be within 1 degree (positive or negative relative) to one another. 3-4 degrees is the upper ceiling. Beyond that, you will get a nasty vibration at speed as the driveshaft, input shaft and pinion spin at different speeds.
Use this calculator below
https://spicerparts.com/calculators/...gle-calculator