The reason it's connected to the axle (and not the diff) is simple convenience. The inside of the tubes and the pumpkin have oil (and vapors) flowing freely between them, so it makes sense to only have one. I suspect the reason for the location is so that if there's any oil spewage, it is by the fuel filler chamber, which is already designed to keep oily stuff out of dangerous places (like the interior). The clip is located just beneath the filler hole plate and you can access it by removing the bolts from the plate and just placing it to the side. The little check-valve on the end can be removed and re-inserted in a like-sized tube. You can also get up behind the filler plate from the back of the wheel well (sort or up inside the bumper cover.
I extended mine by a couple feet with a length of fuel hose of the same diameter and a double brass barbed fitting. You can tie-wrap it up behind the filler and leave the check-valve up inside the body panel. Lash it to something, though, or it'll rattle around and might drive your rear-seat passengers crazy.
Dan
_________________

2005 Silver CRD Limited

245/75R16 GoodYear Duratracs
Fumoto drain | ProVent CCV Filter
Stanadyne FM100 filter | Cummins fuel pump
GDE Eco | SEGR | BoulderBars | FrankenLift | Frankenskids