Your going to have to start from square one because you don't know what size the original shim(s) were or should be.
Start by cleaning all of the junk, debris and gasket sealer off of all the cases and parts.
You want it spotless to be able to measure, inspect, and dry fit all the parts.
Clean and wash parts with brake parts cleaner.
Inspect the bevel gear to make sure this lip is in good shape, as it holds the keepers in place.
Also inspect the teeth on the smaller bevel gear in the inboard case for any damage.
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Next you need to inspect the case for wear or bearing slop here, the bearings should fit snug in the case.
Also inspect the bearings for any non smooth movement when you roll them.
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Now inspect the cases for cracks or deformities, especially in this area.
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This is for later reference this the ONLY place a shim will go, between the case and the bearing.
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