Yoke phasing

These MUST be in alignment. I'm not sure "at what point" it becomes significant, but 10 degrees is a hell of a lot.

Example:

Used to have a Jeep transfer in my old Landcruiser, using Bronco shafts so the slip yoke (spline) was on the shaft

One cold sloppy winter day I had a bad joint, and managed to get under, get the slip yoke off the shaft and change the joint in "record time." But somehow I got the yoke "unclocked" one spline. I just could not believe how bad that thing shook at about 40 mph.

This was probably worse than your car, because it was a short shaft and a fairly steep angle (front shaft)

Also, not having these properly clocked indicates just plain sloppy work by the shop. If they can't properly align shaft yokes, makes ya wonder how good (balance) the rest of it is