Where did you wind up splicing into the third brake light at?
If you'll have the 7 round trailer plug, you have all the wires you need right there.
i have the Recon 26416X LED Tailgate Bar and just got the weather proof splice connectors and taped into the 12VDC, and the reverse signal right there from the back. The brake and turn signals come from the 4 flat connector. I may do all of it by splicing later to clean it up more.
Good luck with yours. Post up pictures when your done.
05 1500 SLT Quad Black on Black | Pace Setter Long Tubes | Magna Flow Cat Back | Doug's Electric Cutout | Custom Ram Air Hood | Spyder LED Tails | Spec-D Black Projectors W/Halos | Flex-A-Lite E-Fan |Jet 180 Stat | K&N CAI | 20 inch wheels | Comp 268 Cam W/6.1 push rods and springs | Diablo Trinity | Custom Tune by Charged392.