before you go ahead with changing the cluster, check the small plug on the back of the diff ( top right iirc) the odometer and speedo are connected through this connection and its very prone to corrosion, if you dont have any luck there then what youll have to do is remove the cover under the steering wheel. if you look through the steering wheel at the piece of plastic that sits underneath the guages it has two threaded pins in it that are secured through the dash with 2 large aluminium nuts behind, if you feel up the back you should be able to locate and unscrew them this will allow you to pop the cover off.
remove the screws holding the black plastic, cluster surround( 2 at the top 2 at the bottom)and remove plastic surround,
this will then give you access to the rest of the screws holding the cluster in place, there are at least 4, this will allow you to then remove the cluster without removing the dash ( note, don't try and wrench the plugs out of the back of the cluster, they have clips on them that you have to undo first)
hope this helps
