Ford F-150 2000 Introduction Manual page 129

The rear seats of your vehicle are equipped with built-in tether strap
anchors located behind the seats as described below.
The tether anchors in your vehicle may be straps on the seatback or an
anchor bracket on the rear edge of the seat cushion.
The tether strap anchors in your vehicle are in the following positions
(shown from top view):
Attach the tether strap only to the appropriate tether anchor as
shown. The tether strap may not work properly if attached
somewhere other than the correct tether anchor.
F150 Regular Cab
F150 SuperCab
F150 SuperCrew
Seating and safety restraints
129