If you look at the above pic of the pro valve on the frame rail, the far 2 right lines run up to my master cylinder. Bottom right goes to the right front disc if your facing the front of the truck. Bottom left goes to the left front disk, line at the back goes the rear brakes. The electric connector i ran through a hole in the firewall and connected into the rear brake lights off of the brake pedal. So when you hit the brakes it kicks off the booster. I have an edelbrock carb so i just ran the vacuum line from the booster into the rear of the carb vacuum. You can use any other vacuum ports you have available i just choose that one to make it look a little better. If your referring to the carb linkage check this link out.
http://67-72chevytrucks.com/vboard/s...t=carb+linkage