Yes, that's what I'm talking about - the bits marked 4 on the attached parts pic (for 147GTA on 2003 ePER CD).
Please excuse me if you already know this - I don't want to appear like a teacher (even though that's what I am
When the drive pinion on the gearbox rotates and transmits forward drive to the crown wheel, it tends to push the crown wheel axially as well. When on the overrun, the axial force is in the reverse direction. Clearly you cannot have significant axial play along the axis of the diff or you would get a loud clonking noise as the load went onto and came off the crown wheel.
What AussieNath's really clear pics show are taper roller bearings that fit in a split housing. You can see that the inner cone and roller race is pressed onto the ends of the diff itself. You can also see the loose outer cones. I don't know whether the bearings are assembled to achieve an axial clearance or a pre-load.
Not knowing the assembly procedure leaves me rather guessing - something I'd rather not do really. The time-honoured way is to assemble without shims then by measuring end float, calculate the correct shims to achieve the desired end result. The rings marked 4 on the diagram appear to be for this purpose.
At the moment, I don't know how the outer cones are fitted either - it looks to me as though the casing is bolted up, the bearing cones push in relatively easily and the retaining plates (the bits AN labels "flange") hold it all tight but I can't say for sure as I only have AN's pics to go on and I'm not getting underneath mine in this weather!
Is my explanation clear? I don't think the other thread is fully complete yet!