The extra washers are for tundras without the hitch.
No hitch, then add washers between the upper end link spacer and the frame.
Like this:
That accounts for two (out of the four) "extra washers".
The other two are supposed to go between the nut and the anti-sway bar (on the lower end link).
This isn't noted in the installation manual
Like this:
The above pics also identify the speed sensor line brackets as being brake brackets.