Alright, I am hooking up all of the lines on the new 3.4 (swapping from 3.0). On the 3.0 I guess it had two fuel return lines, because there are two in the engine bay that run down together along the undercarriage to the fuel tank. The new 3.4 doesnt appear to have two return lines, only the high pressure input line (the one with the fitting), and the return that has the little hose clamps on it. Is this true that the 3.0 had two, and the 3.4 has one? Could I just cap off one of the lines? If so, does it matter which one?

EDIT: Also, I just remembered that the charcoal canister has to be put in as well, where in the system would it go?

 

The 3 lines are........1 main supply line, 1 return line, and a evap line that runs to the charcoal canister

 

dwh91102 is correct see this Link on what lines go where. I went through the same thing as you with my 3.4 swap.
Good luck on your swap and post up some pics.