it goes from the MC to the prop valve, then Im not sure what happens whats the line goes into the prop valve, I have people telling me its the thin line then I have people telling me its the thick line, from the looks of the prop valve I would say thicker line but I cant say it for sure becuase I have people telling me its thinner line, this is my first time getting this down and dirty with brakes so i just want to make sure, for saftey reasons, this is my brakes we're talking about ya know, the Wilwood 10LB residual valve only fits the thinner line too, but I called Wilwood again today and they said there are adapter fittings to make it fit the bigger line, they also have no clue what line goes where, even though they make the Kit for a G-body