Sorry, but I'm going to reply to your questions here in a different way perhaps to what you are looking for.
Just stepping back here, some of the late Gearbox Cases used Gaskets on the Diff Cap and some did not. You need to measure to check for that and don't work on any assumption if when stripping the gearbox any gaskets were or were not fitted. Here's an FAQ on the subject, including the factory's advice;-
https://www.theminif...kets-important/
The Gaskets you buy today may not always be the same thickness nor comprehensibility as the originals, so where ever in any many they may state a particular fitted thickness for a gasket, you should in fact check what fitted thickness you'll end up with, using the gaskets you have.
To shim up the Diff in order to pre-load the Bearings, I fit the diff to the case, biased towards the RH Side (the side away from the Crown Wheel),then Fit the Diff Cap, bring the nuts down to the Spring Washers, compressing them a little but not nearly tightening them, so some light pressure is applied. You may wish to do this without RTV or sealant the first time around, as you generally only have 15 - 20 minutes working time with them. Then fit up the Side Cover (no shims) with a gasket on the RH Side and this should then push the Diff Assy back towards the LH Side. You should be able to measure the Gasket's fitted thickness on this side for a Gasket Thickness on the other (assuming you are using the same Gaskets on both sides). Then fit up the LH Side Cover with no Gasket to start shimming. I find it faster and more accurate to shim by 'trial and error' rather than measure, but if you only have a small number of shims to hand and need to likely buy shims, then you need to measure. To measure, fit a much thicker shim than you'll need. This maybe a 20 thou or a 20 + a 10 thou shim. This should leave a gap between the flange of the cover and the case, which you can measure. Put the bolts in and tighten them with your fingers until they touch the side cover and no more, to hold it in place and square it up for measuring. Check in a few places as often the covers are distorted. Make a measurement, some basic maths and you can work out what shims you need.
Here I depart a bit from the Manuals, especially when there's variation. The covers are only thin and light ally and will flex quite a bit, so I prefer to fit them up on the tight side rather than the loose side. While the manuals say for the non-thrust bearings only 1 - 2 thou preload, they are quite happy with more than this. These are a deep groove type (ordinary) Ball Roller Bearing. If you look up the Bearing Manufacturer's charts and tables, these Bearings will happily withstand quite high side loadings, far in excess of anything you can 'make' when fitting them in to the Mini Gearbox Case, you'll be stripping threads long before you get anywhere near overloading them. I prefer to have them tighter rather than loose to prevent movement of the Bearings in the Case (which will only wear the case and lead to oil leaks) and also to be sure the Diff Assy is at all times, held parallel to the Mainshaft (and so the Final Drive Gears meshed correctly together loading the whole tooths where they contact rather than on the tips). I am happy here to have 0.002 - 0.003" Preload. Having more preload - or rather what looks like more - won't show up as any extra Pre-load but as distortion to the side covers.
Shims are available in 0.003, 0.006, 0.010 and 0.020". Mini Spares may no have all these sizes in stock.
