Just to expand on what KlingonFiero said, there are two wire bundles on the side that go to the side switches, you have to take them out first.
Then there are only three connectors for the rest of the cluster, one on either side of the back and then one on the lower bottom of the left hand side.
If your cluster is old, (and they all are) those traces on the back of the printed circuit board thingy are going to want to break so you have to be carefull. If they do break you can either try to repair them, or just solder a wire directly to where it needs to go. I had to repair a few in the past to get my dash lights working.