@Stretch - I am following your 201 diff rebuild thread It does cover measuring friction on the drive pinion. I remember one of your threads about adjusting a steering box and a very clever wooden ruler type thing and weights
Would it be possible for you to measure friction with the crown wheel and differential assembly installed to get an idea on how much the friction increases from 50-100Ncm.
You are right about everything.
Without removing the crown wheel and differential assembly from the casing i will not be able to accurately measure friction load of the drive pinion.
It's hard to guess what the friction load should be when the crown wheel and differential assembly are installed. My guess would be certainly above 100Ncm since with the drive pinion alone it's 50-100Ncm.

The FSM chapter 35-530 says that minimum torque for the shaft nut should be 180Nm. This is the starting point for further adjustment.
Thanks to your suggestions I have decided to do it the following way:
-Torque the new pinion nut to 180Nm
-Measure friction on drive pinion nut
-Assess the contact patch of the pinion and crown wheel gears using engineer's blue

After that I will either be OK or will have to make adjustments.