So the shimano HG free hub body is a smaller diameter than the XDR, so I guess the hub is XDR compatible only unless the shimano come in variable diameters? It’s from a set of Fulcrum 800DB
That doesn't matter, as both freehub bodies will fit over the axle of the wheel. Fulcrum catalogue says you need freehub Ro-202 for your wheels. Should be easy enough to find online.
So the shimano HG free hub body is a smaller diameter than the XDR, so I guess the hub is XDR compatible only unless the shimano come in variable diameters? It’s from a set of Fulcrum 800DB