"Sorry, incorrect, but there are factors involved. If you remove the axle tube that contains the diff side bearing and add a gasket then reinstall without adding shims behind the bearing cup (the same thickness as the gasket) you will have altered the diff side bearing preload. BUT if you rebuild the differential and set the preload based on the thickness of a gasket then yeah no affect as you say, but that is not how 99% of Alfa diffs are setup and in this case they were trying to remedy a leaky diff, not rebuild, so if there is now a gasket or thick gasket goo we have a problem that needs to be fixed immediately."
Pete this is correct as well. My point was removing the AXLE TUBE (not the diff side case cover) , the one on the other side small diameter one, has no influence at all on anything other than spline engagement. Without a doubt, removing diff side case with bearing as you point out and adding a gasket
will change crown wheel preload
74 GTV with 10548's and Ingram pump
71 Spider 1750 BOMBER ; 1995 LS 78K tight fast car