Hi Mark,
Thanks for your post.
The catalogue I have suggests my rear axle is the one below. See attachment. I include a couple of photos too. In the photos the bolts on the inspection cover appear in both photos which hopefully makes it possible to navigate between the two.
Item 10 on the catalogue picture is the ‘gasket’ and the catalogue suggests 11998-2. Which is also the gasket for the oil sump. The drain seems to be on the underside.
Gasket measurement are as follows, outer diameter, inner diameter, thickness, all in mm.
947624 is 21.7 18.3 1.5.
957181 is 21.9 18.2 1.5.
11998 is 23.9 18.5 1.5
Oddly the catalogue I have does not depict a washer/gasket for the oil filter 3517857. I generally use the washer that comes with the oil filter but maybe one should not use them?
Gasket/washer measurements sourced from SLP.SE
https://slp.se/en/specifications/volvo/11998