Marion, the car I installed this in is my 72 Cuda and it has the 71 style ECS system. I tapped into the second (second shortest vent in the ECS) so that fuel in the lowest level of the seperator ouldn't settle into the vent return line. I think it works. I will then plump the line that runs to the engine bay from the ECS to the engine (it would normally go to the charcoal canisteron a 72) The diagram is for a 71 Cuda
NOTE: The command center vent WILL RETURN SOME FUEL to the tank. FiTech states the vent line back to the tank MUST be above fuel level. I think most folks tap into the filler neck, the logistics of doing this on the Cuda didn't allow this very practically.