I was reviving a old Dyson V6 that was missing the cap and shaft to hold the brush in place.  As you can see from the picture it is V6 variant that has the lower profile head/brush unit.  You will need a standard bearing to couple the pieces together.  

The shaft will need support

The cap has 2 small extrusions that will allow it to twist and lock securely in place.  

The tag lists 60865 but it shows both variants.