69 Dart fuel system question

It's diagrammed right in the FSM. You can download one here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

It runs down along the filler tube, down through a hole in the plastic? rubber? cover on the trunk floor and ends INSIDE the frame rail. That is, there's a hole in the top of the rear frame rail, it just pokes down in there

VERY important to have a tight seal around that floor gasket to keep fumes out.