This is for the 95-97 clusters but I believe the 94's are the same way. There have been quite a few times people have asked about swapping out their non-tach cluster for one with a tach. The main issue is finding one with close to the same mileage and one for the correct engine, since the 4 cyl and V6 have a different RPM range.
Well heres the way to fix the mileage issue. Swap your current odometer with the original mileage the one from the cluster with the tach.
1st you need to find a cluster to swap out. There are plenty on Ebay or Junkyard.
To remove the cluster, remove the dash bezel. Then the cluster (4 torx head screws). Ive heard that some can get the cluster out with out having to lower the steering column. I, myself, had to lower it.
Front of cluster, remove 4 torx head screws, remove clear plastic cover
Flip cluster over, there will be metal clips holding the contacts for each gauge (circled in red). The gauges are all mounted to the faceplate of the cluster. The pin in the middle of the clip is the gauge contact, push on the pins slighty to losen them up. once you ahve all the contact pins out the whole faceplate will come off.
Now you need to remove the odometers from both clusters.
This is the circuit board for the Speedo/odo cluster. First you need to remove small torx screws then put out the contacts like you did for the cluster itself.
This is the circuit board for the Tach/odo cluster, same deal with this one. Remove a few screws, the push out the contacts
Now you need to remove the motor/odo from the cluster. The needle needs to come of to remove this.
This is what the odo looks like after removed. This is as far as you need to break it down.
All you need to do now is take the odo you removed from your non-tach cluster and install it in the cluster with the tach. Installation is the exact reversal of removal.
Although you are now taking the motor used as the speedometer and using it as the tach. It will work as the tach.
Well heres the way to fix the mileage issue. Swap your current odometer with the original mileage the one from the cluster with the tach.
1st you need to find a cluster to swap out. There are plenty on Ebay or Junkyard.
To remove the cluster, remove the dash bezel. Then the cluster (4 torx head screws). Ive heard that some can get the cluster out with out having to lower the steering column. I, myself, had to lower it.
Front of cluster, remove 4 torx head screws, remove clear plastic cover

Flip cluster over, there will be metal clips holding the contacts for each gauge (circled in red). The gauges are all mounted to the faceplate of the cluster. The pin in the middle of the clip is the gauge contact, push on the pins slighty to losen them up. once you ahve all the contact pins out the whole faceplate will come off.

Now you need to remove the odometers from both clusters.
This is the circuit board for the Speedo/odo cluster. First you need to remove small torx screws then put out the contacts like you did for the cluster itself.

This is the circuit board for the Tach/odo cluster, same deal with this one. Remove a few screws, the push out the contacts

Now you need to remove the motor/odo from the cluster. The needle needs to come of to remove this.

This is what the odo looks like after removed. This is as far as you need to break it down.

All you need to do now is take the odo you removed from your non-tach cluster and install it in the cluster with the tach. Installation is the exact reversal of removal.
Although you are now taking the motor used as the speedometer and using it as the tach. It will work as the tach.