Here are the part numbers for the 02 sensors and a TOTAL OF FOUR are required on the 13+SHO.
I found the best price @ www.rockauto.com with Promo-code attached below.
Z
THE FRONT PRIMARY 02 SENSORS HAVE THE SAME PART NUMBER & TWO ARE NEEDED.
MOTORCRAFT DY1185- 8F9Z9F472H
$59.79
THE DOWNSTREAM FRONT 02 SENSOR ONLY REQUIRES ONE SENSOR
MOTORCRAFT DY1155- BH6Z9G444A
$52.99
Here is a PIC of of the DOWNSTREAM FRONT SENSOR which is located underneath the oil filter for reference. Z
THE REAR DOWNSTREAM 02 SENSOR REQUIRES ONE SENSOR.
PIC BELOW.
MOTORCRAFT DY1167- BA5Z9G444A
$36.79
I found the best price on www.rockauto.com with Promo-code below.
https://www.rockauto.com/en/catalog/ford,2013,taurus,3.5l+v6+turbocharged,1503823,exhaust+&+emission,oxygen+(o2)+sensor,5132
Promo-code 7101DF2E857469
Expires: June 26, 2018
I found the best price @ www.rockauto.com with Promo-code attached below.
Z

THE FRONT PRIMARY 02 SENSORS HAVE THE SAME PART NUMBER & TWO ARE NEEDED.
MOTORCRAFT DY1185- 8F9Z9F472H
$59.79
THE DOWNSTREAM FRONT 02 SENSOR ONLY REQUIRES ONE SENSOR
MOTORCRAFT DY1155- BH6Z9G444A
$52.99
Here is a PIC of of the DOWNSTREAM FRONT SENSOR which is located underneath the oil filter for reference. Z

THE REAR DOWNSTREAM 02 SENSOR REQUIRES ONE SENSOR.
PIC BELOW.

MOTORCRAFT DY1167- BA5Z9G444A
$36.79
I found the best price on www.rockauto.com with Promo-code below.
https://www.rockauto.com/en/catalog/ford,2013,taurus,3.5l+v6+turbocharged,1503823,exhaust+&+emission,oxygen+(o2)+sensor,5132
Promo-code 7101DF2E857469
Expires: June 26, 2018