Just found out a bit more about this.
The sleeve was there on some models as a mesure to prevent the alloy splitting or deforming when the bearing was inserted (from the bottom up on these ones)
The washer seems to come in both bush or no-bush variants, and is a simple dust/grass/debris cover for the bearing, to prevent grass, plastic or rope making it into theactual bearing.
It seems the non-bush, and bush type dust washers are interchangeable.
