Factory disc trucks have the lines on the front side where the drum brake ones had them to the rear of the crossmember. When I converted my C10 panel, I made new lines for the front and mounted a bracket in the approx. location that a stock disc brake setup would have. This routes the soft line from the front to the rear and keeps any tight bends out of it and allows freedom to move as the suspension cycles up and down.
Sorry for the blurry pic but this is the bracket I mounted.
