2003 Third Brake Lamps--1-, or 2-wire setup?

[TxDoc]

There appears to be two wires on a plug that contains four total on the end where the third brake light and cargo lamps are. A black and light blue appear to lead to a copper strip that runs beneath the stops lamps and the other two wires appear to lead to the cargo lamps. On the brake pedal end, there is a plug with six wires..

I have two sets of install instructions that requires you to decide if you have a 1- or 2-wire connection to the third brake lamps.

If anyone has any ideas on a 2003, let me know.
Thanks