Hi,
From my experiance, the 97/98 ST24s seem based on Ghia Xs, and have 13 wires for computer, but the 99/00 cars, like mine, have slight differences, mine only had 5 wires.

As said, you will need an outside temp sender, quite cheap from scrappy, but to get fuel remaining you need a special fuel pump, which are pricey from Ford and becareful as so called special fuel pumps from Mk1 or early Mk2 mondeos can give you fuel remaining, but the fuel gauge in the dash will read backwards!!!

I got all mine working, except the fuel remaining, and had to do a bit of wiring, but I've given up on the fuel remaining as unless you can buy the complete set of trip computer, temp sender and fuel pump, so you know it all works, then getting the right fuel pump can be bit of a lottery.

Good luck, if you've got 13 wires to the clock you are laughing, it's just plug and play.