Front hub - not a hub nut, but a sort of inverted hub nut?

[VerySideways]

Help - on my G33 front hubs rather than there being a hub nut there is a sort of circle with a nut shaped hole in it - looks to be somewhere around 40mm or so (i should have measured it!).

Anyone know what this is off, or what specialist tool i need?

Thanks.

[Broomsticklady]

Tried posting on owners club website?

[VerySideways]

Spoke to a mate who knows Cossies, turns out the hub nut is on the inside of the hub, not on the outside! (it's a rwd Cosworth front hub you see)
Just purchased the required 41mm socket.

[VerySideways]

Job done - if anyone's doing this job themselves in future, pictures and write up here:
http://www.verysideways.com/pages/g33_fwbr.htm