I AM NOT familiar with this exact vehicle, but as far as the petcock goes, if the radiator is plastic, there may not be one at the bottom. You may just have to remove the bottom hose and drain it from there. As far as the thermostat goes, ask a Ford dealer or invest in the big orange book called "CHILTONS". You can find a Chiltons at major automotive stores. The book is expensive, but well worth it if you do your own repairs on a regular basis. GOOD LUCK
look at the bottom or rear of radiator
The thermostat on a 1997 Ford Aspire is located on the engine, specifically at the end of the upper radiator hose where it connects to the engine block. To access it, you'll need to remove the upper radiator hose and the thermostat housing, which is typically held in place by bolts. Make sure to drain some coolant before starting this process to avoid spills.
under the distributor cap there is a pipe bolted to the engine. the radiator hose is attached to it. take those 2 bolts out of that pipe and the thermostat is under it.
There are three sensors related to coolant temperature on ford aspire - one for dash gauge, another one for the radiator fan and the third one for the ECU. The one which controls the fan is mounted on thermostat housing - so, it is the closes to where upper radiator hose meets the engine.
Head Gasket
this site^ will show you a how
It is under the distributor. Look for the upper coolant hose (it's about an inch thick) and you will find the thermostat housing.
blown head gasket
Under the radiator on the left side. U have to jack up the right side to easily access the plug.
The crank sensor is located on the front side of the crank pulley, between the pulley and radiator.
To change the antifreeze in a 1997 Ford Aspire, first, ensure the engine is cool and then locate the radiator drain plug at the bottom of the radiator. Place a container under the radiator, open the drain plug, and let the old antifreeze drain out completely. After draining, close the plug, and refill the radiator with a 50/50 mix of new antifreeze and distilled water. Finally, run the engine with the heater on high to circulate the fluid, check for leaks, and top off if necessary.
right side of trans, below battery, 2 trans fluid lines connect to the radiator.