On a 1997 Ford Taurus wagon :
Open the rear liftgate and you will see a fill plug by the passenger side
This doesn't totally answer your question , but on a 1997 Ford Taurus wagon you refill the liftgate washer fluid reservoir by opening the liftgate and you will see a rubber plug below the passenger side taillight . So the reservoir for the rear windshield must be behind the interior trim in the cargo area
It is important to maintain the quantity of the transmission fluid of a 1997 Ford Taurus. The transmission fluid capacity of this vehicle is 13.3 quarts.
It is on the bottom of the washer fluid reservoir.
On the bottom of the washer fluid tank.
Starting with the 1997 Ford Explorer the rear washer fluid is supplied by the windshield washer fluid reservoir in the engine compartment
According to the 1997 Ford Taurus Owner Guide : ( all models have a 60.6 litre / 16.0 U.S. gallon tank )
According to the Owners Manual (See "Related Questions" below), the 1997 Taurus holds 11.6 quarts, or just under 3 gallons of 50/50 anti-freeze/water mix.
Take it to the mechanic
That should be Motorcraft MERCON automatic transmission fluid in the automatic transaxle ( transmission ) according to the 1997 Ford Taurus Owner Guide * the type used is engraved into the automatic transaxle fluid level dipstick
I have a '98, and when the "LOW WASHER" light comes on and it finally runs out of fluid, I can put almost a full gallon into the reservoir.
You have to remove the washer fluid reservoir and remove the pump from the bottom area of its side.
It's located near the bottom on the side of the washer fluid reservoir. It's a little cylinder and it's got a cable running to it and a rubber washer fluid hose running out of it.