A8 speedo help

Now ive been having a dodgy connection somewhere and my whole dash goes out with nothing working every now and then,,and then it comes back on weird..
Now to my question i have been looking, and i found one..but....can you fit a S8 98 dash (speedo,rev,vdo) to a 98 sport quattro as it seems a reasonable price..
Does it come out ptretty easy and does the new one fit the old connections.