Well, it kind of is a mix of Mark VI and ODST, seeing has he has Mark VI chestplate and shoulderplates, but an ODST helmet. Anyway, Noble Six and all the other SPARTANs in Reach have Mark V armor, like MC in Halo 1. Noble Six has a Mark V [B] helmet, tho.
I take it you don't own Halo 3 multiplayer?