si gage cluster
 

i tryed puting a 91 civic si cluster with tack in my 89 civic dx and it didn't work.why?

because the 88-89 has different plugs then the 90-91. you can depin the wires and get 90-91 plugs or you can find a 88-89 cluster and it will plug right in.

you should visit honda-tech.com more often.