To be absolutely certain, you should:
* Check the part number: Find the alternator part number on your 1999 Taurus (usually stamped on the alternator itself) and compare it to the part number for a 2000 Taurus alternator. Online auto parts stores will list this information.
* Consult a parts catalog: Use a reputable online parts catalog (like AutoZone, Advance Auto Parts, or Napa Auto Parts) and enter the year, make, and model of each vehicle to compare the alternator options.
Simply assuming they are the same could lead to an incorrect purchase. Take the extra few minutes to verify the part number for accuracy.