A few things to look for:
-Don't get a gauge cluster off of an SR5, GTS, or Geo Prizm, they're all the wrong shape, and won't work.
-You need to look for a gauge cluster out of another wagon or sedan (high trim line cars have them, like the LE for example.)
-The wiring should work just fine.
-You may need to have a shop swap out the odometer from your current cluster to the new one (you don't want to tamper with the odometer now do you?)
-eBay is a wonderful place to find things like this.
edit:
quick search on eBay found this:
http://cgi.ebay.com/ebaymotors/1991-...13384261QQrdZ1