Have a 2001.5 Discovery on a FL XC Chassis with Alcoa rims. During the process of polishing the wheels I discovered that the rear hub covers are held in place by the Freightliner Logo which has a threaded bolt cast into the reverse side. In a attempt not to mar the chrome finish on the emblem I made a removal tool from a 3" dia. PVC pipe cap. I cut the pipe cap using my drill press and a router bit. The finished product works great.
While removing the hub centers I discovered that both are right hand threads and lock in place with four nubs which engage the chrome hub covers which have four indentations in the cover face. I'm adding some pics for clarification.

Center Emblem

Bottom of Emblem showing nubs.

Axle Cover with indentations

Side view of Emblem bolt.