Yes, like was said, if you are just swapping the speedo mechanism part of the cluster, you can do it, but it does require some trimming, cutting, filing, and drilling of a new locator hole. I put one from a 92 GT in my 87 cluster. It took me about 15 min to adjust it to fit the 87 cluster. It fits, but the color and texture are a bit different and the turn signal arrows are different sizes.
As for the whole cluster, it will fit also, but almost all of the wiring is different, so you would have to rewire the connectors to match the newer cluster.