okay, the long slender thing that all of the lines go into is the proportining valve, mine does not have a bleeder on it some do, and some master cylinders do also. What gordo was referring to was the two lines that come out of the master cylinder. But if you have a prop. valve that has the bleeder on it use that, if it is a new master cylinder then usually it will come with a bleeder kit ( two fittings, two clear hoses and a clip, so you could bench bleed it while on the truck. If it doesn't have a bleeder and you don't want brake fluid then I would recomend using the wheel cylinders and bleeding it that way, and as far as starting with the furthest wheel away, I have also read in the Chevrolet Service manual to bleed it from the closest wheel first, so as not to push air into the rest of the lines.
