WARNING! The 97-01 clusters are not exactly the same. From what I experience and have heard, there are some slight differences between 00-01 and 97-99 clusters. If you have a 97-99 XJ, then you should try to use a cluster from the same years. If you have a 00-01 XJ, then you'll want a cluster from those years.
I have a 97 cluster (from police package 'certified'...120mph speedo vs. just 100mph) in my '00...it was plug and play...all of the gauges work and most of the idiot lights work...BUT I lost my 'rear hatch ajar' warning light and my 'low washer fluid' warning light doesn't seem to work right either. But these are minor issues compared to having tach and the rest of the instrumentation.
Also, I've heard that if you have a 242 t-case and you put in a cluster from an XJ with a 231 t-case, you'll need to make sure that 'full time' light bulb is present and working.
As for reprogramming the mileage...I had it done (when I was living in Cali) by Kris's Mobile Speedo Service. The guy had the mileage reprogrammed within a day and cost $120 at the time...about 3 years ago. Not sure if he is still in business, but his contact info at the time was
[email protected].
Or you can find other 3rd party places that do it on google.