locking the flange to differential carrier

[Quinlan]

Hello transmission gurus
I am reassembling my 915 transmission using Mr. Zimmerman's tutorial and I have run into a snag.
First a brief background. I disassembled the transmission about a year ago. I had a friend who is a machinist remove the old carrier bearings and re-install new ones.
Since then, the project has sat in boxes. Now I am finally getting around to working on it.
I have followed the directions up to the point where I am to use a torque wrench to measure preload. I am getting zero - the diff spins freely.
Before I disassemble the unit to add a spacer, I am trying to understand the concept of "locking the flange to the bearing".
When I am trying to measure the preload, I am using a homemade washer in place of the Porsche special tool P357.
My first question is - is this washer simply a spacer, or is it supposed to press on a part of the bearing? The tutorial says that the outside measurement of this washer is 45mm. The outside diameter of my washer is less than this, however when i look at the interface of the axle flange to the carrier, I can't see that there would be any difference between a washer which is 38mm to one which is 45mm - in other words the washer acts as a spacer only (?).
My second question is whether there is a way to tell the thickness of the shims installed under the bearings without removing the bearings (or whether any shims are installed). After a year since installing the bearings, naturally my friend who installed the bearing can't remember if he replaced the shims.
I'm attaching a picture showing my homemade spacer - is the outside of the space supposed to extend out to the first ring of the bearing?

[Quinlan]

Any of you transmission guys able to help me?