Adding Pinion Angle Shims - Tell Me If This Sounds Correct, Please

JMO, I would measure off the output shaft if it is sticking out from the gear vendors. Not sure if anyone else mentioned that. If the yoke doesn't have a flat surface machined into it, I would not use it to obtain the trans angle. Whatever the trans angle measures, down 3*, you want the pinion UP 3* for prallel state, then roll it down to obtain the "roll up" variance. Your math approach looks correct.

Dr Diffs parallel comment is when the vehicle is under power. Static you want the pinion to be down slightly as it will "roll up" under power. It's why they put pinion snubbers on cars, to plant the tires using the rotational/roll up forces under acceleration. I agree with the other poster, I use snubbers as door stops to allow a breeze in the shop, save the environment a little and not in a landfill.

I've worked on some drag cars that had stupid levels of pinion down in them. Most passenger cars are good in the 1-3* down range. 2* down is a good starting point for a street driven car. More power in the engine, roll the pinion down a smidge more. Too much and you may induce vibration. It's a balancing act.

Your diagrams, pinion on most passewnger cars is lower than the output shaft level. Driveshaft almost always points down going to rear of vehicle.

Pinion angle is where you get 10 bazzilion answers and none of the right... LOL That's sarcasm for the few that want to start in on it! Looks like you got it.