90 swap to 91 cluster,tach will not work

Swapped out a 90 tach-less cluster for a 91 cluster w/tach both are for 4 cyl. The problem is the tach and oil pressure is not working. Is there a wire I need to add or something. I read some where (many moons ago) you can swap and everything would work, not true. My truck has a 22R not RE, that may be why, can anybody that had this help? thanks

Assuming the new cluster is good, more than likely your wiring harness doesn't have the wire for the tach (esp since it's a 22R, and RE would need that signal).

You can run a wire from the connector on the coil up to the cluster. A Factory Service Manual will have a pin out diagram of the connector on the cluster.

If you didn't get the oil press sending unit along with the cluster, that would be why the gauge isn't working. The idiot light sender will not work with the gauge. There's a possibility it may have also damaged the gauge.