98 mac headers
Yes they would fit, but you might have a hard time getting the AIR/EGR to line up. If you delete that crap, you wouldn't have to worry about it. Check the AIR/EGR sticky for more info on that.
I gave my 98 macs to a buddy with an 00 TA and they fit fine. Like Blur said, the emissions fittings are the only thing that's different. You can either delete the emissions and cap the fittings on the headers, or modify the 2000 fittings to hook up to the 98 fitings. My buddy wanted to keep his emissions stuff, so all that was needed was to make the driver's side AIR hose longer (we used heater hose) and the EGR tube needs to be cut shorter and bent a little. The tube is easy to bend, it's made of "flex" pipe with the ribs that keep it from kinking. If you have any problems just let me know and I'll help ya out. 
