I would think you would have both. My 400HO has both a fuel line and a vapor/return line from the fuel pump to the tank. One runs in front of the cross-member and one behind. I cannot remember the which is which.

Here's a diagram in the Parts Illustrations Book (about 1/2 way down and on the bottom left of the fuel line illustrations) that shows the lines and the hose sections.
http://1968firebird.org/illustrated/carb/carb1.html

And here are some, not very clear, pictures of my fuel lines: http://www.geocities.com/jims68fb/FuelLine.html