"I'm with you Cab... the rear end is constantly moving
so how can the 2 U-joints be equal at all times..
granted when I build a chassis I line the centerline
of the engine/trans up with the centerline of the pinion
with it at zero to the driveline then I roll the pinion
down X dergees for the style of rear suspension....
I hate to get involved in this question... there are
the 2 theories to it and no one agrees with the other"

Exactly. This subject has been argued several times without much give from those that are wrong.
After my experience with severe pinion angle due to axle housing tube slippage, I can understand why folks aren't willing to change their minds. Damage didn't occur till pinion angle was off by 20 to 25 degrees up. But then it took out the trans.
If you think about it, Chrysler was able to recommend as much as 7 degrees down during coast for leaf spring cars. That would lead me to think there is at least a 7 degree window the other way where it may not be close but damage wouldn't show itself for an extremely long time.