There are two different digital clusters they used and one really isnt worth it to install. Theres an ancient thread around here that discusses how to make an adapter harness with all the pinout info and I sort of made a diagram for my particular 1994 3100 CS to use that I can dig out and post a pic of that might help you out. If you didnt clip the harness out of the car with a legnth of wire you better get back there and get it. You will also need to break open an analog cluster to get the plastic connector as well if you want to build a harness without repinning your cars wiring harness.
Heres Nate`s thread and its probably the best source of info for that swap.