From what I've been told just the odometer itself, but it's no servicable seperatly, You have to buy the entire thing.
you might want to check around and ask about the 94 swap, heard it was pretty easy, but that there was a little diffrence in the two. I have also heard the the speedo is like 150.00 from ford, or something like that.
I haven't done the swap yet myself however, so I can't be of much insight there.
Good luck
Tim