Hi Craig,
On the 3.8S you already have a big fan behind the rad. with a good shroud and turned directly by the engine. If you have cooling problems, i'd look elsewhere to fix it - water pump, thermostat, radiator, or your gauge/sending unit may be giving wrong readings. If you do add a fan, DO NOT mount it through the radiator fins with the plastic pins. The vibration eventually ruptures a tube. Make a bracket to mount it somewhere else. The only people that like them are radiator repair guys - job security.
Phil.