Grigg - my post says nothing about measuring anything (????)...
Could be we're talking about the same thing in different words?
As I read it the issue I have with your instructions are as follows:
...Put an angle finder on the bottom of the starter, front to back. Read the angle. Put the angle finder on the drive shaft just in front of the rear u-joint, front to back. Turn the rear end.. until the angle becomes the same on the angle finder as the angle was when the angle finder was on the bottom of the starter...
If the angle finder reads the same on the bottom of the starter as it does on the driveshaft, then they are parallel, the U-joint operates in a straight line, no angle change.
In simple terms the
pinion needs to be parallel to the starter, not the driveshaft, or more accurately the pinion needs to be parallel to the transmission output shaft (starter is close but may not be exact).
Again, I suggest anyone doing this first read the instructions from Spicer which are found in the tech tip.
There are many different situations and coresponding solutions for driveshafts, giving a clean clear answer here is difficult to do as seen by this example, better to read how and get the info "straight from the horses mouth".
Grigg