How do you replace a thermostat on a 1999 mercury sable dohc?

Here ya go!

3.0L DOHC VIN S Engine
CAUTION NEVER open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities.Always drain coolant into a sealable container. If necessary, clean coolant maybe reused unless it is contaminated or more than two years old.

1. Drain the coolant until the level of the coolant is below the level of the thermostat.
   
2. Raise the vehicle and support it with jack stands.
   
3. Disconnect the lower radiator hose from the water inlet connection.
   
4. Unfasten the two water inlet connection retaining bolts and remove the water inlet connection.
   
5. Remove the O-ring seal and thermostat from the water inlet connection. Inspect the O-ring for damage and replace as necessary.
   

1. Clean the water inlet connection mating surfaces.
   
2. Install the O-ring, thermostat and the water inlet connection. Refer to Figure 10 if you can't remember how the O-ring and thermostat are positioned.
   
3. Install the water inlet connection assembly retainers and tighten them to 71-106 inch lbs. (8-12 Nm).
   
4. Connect the lower radiator hose to the water inlet connection.
   
5. Fill the engine with coolant, start the engine and check for leaks.
   
6. Stop the engine and top off the coolant recovery reservoir as necessary.