Ive been reading about negative switches, 4 pole relays, getting wiring blessed by a pope, all kinds of stuff to hook up a 3rd brake light. I went out and tested my wires on the 50". There are 4 wires on the plug for the rear lights.

Brown-ground
orange w/ brown trace – test positive when brake is pressed
orange – test positive when brake is pressed
red w/ yellow trace – key on hot (running lights?)

I hooked an LED strip to brown (ground) and orange (positive) and the LED strip lit up brightly when the brakes were applied and turned off like it should.

Further inspection I noticed that although there are 4 wires at the rear plug, there are only 3 wires at the rear bulb. I found that the orange w/ brown trace turns into an orange w/ white trace and goes to the right side while orange stays orange and goes left.

So here is my updated wiring description
Brown-ground
orange w/ brown trace – right brake light (turns into orange w/ white trace)
orange – left brake light
red w/ yellow trace – key on positive (running lights?)

So it would seem that if you want to run a 3rd brake light its as simple as tapping into one of the orange wires. Can anyone confirm this?