I swapped my 86 cluster with a 91 burb cluster. Had to repin it, was not hard. I have a spreadsheet somewhere...
After repinning, only thing you have to hook up from your harness is the speedo wire, and that pins into your cluster "plug".
I can email you my spreadsheet if you want, hope you can understand it. Best thing to do is if you have it, the cluster plug with all the wires from the 91 cluster, take out one wire at a time from your old "plug" and color match to new "plug". Hope that makes sense.
Let me know.