Are you talkin about an ae92 csi? Well I went through the same ordeal a year or so ago. I couldn't find an SX cluster so I went with one that had a tacho. I'm not sure what car it was from cause I have yet to see another ae92 with the same cluster. But it came complete with the annoying speed chime when u hit 105 km/hr.
Anyway they are not plug and play !! Read on the forums that they would be... but spent the whole weekend taking apart the cluster and tracing wires from the old cluster to the new.
All I gotta say is what a headf*ck ! And good luck !