When I designed my replacement harness, I split everything up to the rear. I like to isolate the brake and turn signal circuits so I have a totally visible brake lights, when my turn signals are flashing. It takes a little more wire from front to back, but I feel more comfortable in traffic. The large 4 " LED truck lenses are running and brakes, while the amber LED on top of the running/brake lights and the bed rail light, are dedicated turn signals.
I liked the screw-off cap on the rail lights...you can get in there to change the bulb...the main body is tight enough so I'm not going to have some idiot stealing them and if they do take the cap, I can replace it easily and for pennies.
Ubetcha Cletis...creating you own stuff is half the fun of building. To save you a little looking....the tubing used in a boat seat post extension fits...the 1/8" outer edge could be rounded and polished..."O" ring front and back could snug in the lens and you'd be in business.
Think I'll just keep that $100. bucks in my own pocket!!!
Dave