Check all fluids including AT, PS, coolant, brakes and even if they are within normal range note their level for a baseline and continue checking them. Look around the back of the engine/firewall area where the heater hoses are routed. If you have car ramps you can get underneath and really check it out for where it could be coming from. Whatever is leaking could be coming from somewhere else and just running along a path until it finally drips off.
2004 Sable LS Prem DOHC
2001 Taurus SES DOHC
Previously owned:2000 Taurus SE, 1994 Sable GS, 1988 Taurus LX