There were 2 primary type engines in those years - which then has 2 slightly different arrangements to the various components under the hood.
As a general statement, look to the back right corner, below the air intake ductwork.
For specific and illustrated location, check page 128 & 129 in the 1998 Owners Manual.
See "Related Questions" below
In a 2002 Ford Taurus the type of automatic transmission fluid to use is indicated on the automatic transmission fluid dipstick or the dipstick handle
Near the firewall , between the engine and transmission ( transaxle )
On a 2001 Ford Taurus : The automatic transmission fluid dipstick ( fill tube ) is between the engine air intake tube and the engine compartment firewall
I can't answer re. all cars, but the transmission fluid dipstick in my Ford Taurus is as easy to get to as the oil dipstick. Since the transmission fluid also often needs checked frequently my guess is it is usually as easy.
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
There is not an external transmission fluid reservoir - fluid is added through the dipstick tube.See "Related Questions" below for more
through the dipstick tube. using a small pointed funnel.
You actually have to put it into the transmission fluid dipstick hole using a long funnel. I just did this tonight after speaking with my mechanic.
The Owner Guide shows ( Motorcraft MERCON - V ) automatic transmission fluid ( fluid type is shown on transaxle dipstick or the handle )
How much transmission fluid does a 2001 ford Taurus need
The dipstick cover is labeled Transmission Fluid. Transmission fluid on a 2000 Ford Mustang is added in the neck of the dipstick tube after the dipstick has been removed.
Starting in 2002 the Ford Explorer 4 door does not have an automatic transmission fluid dipstick