It will have to get reprogrammed, I know its a VZ cluster thread but it may help u out abit. http://forums.justcommodores.com.au/vz-holden-commodore-2004-2006/84344-conclusive-answers-about-vz-clusters.html PM Phreddy as well, he'll give u all the know how!
if you have a series one you will need a series one ss cluster and if you have a series two you will need a series two or the fuel gauge wont work very well and you will need to have some other things changed in the cluster like the number of air bags, set it to a v6 from a v8