[SCOTI]

I ran mine through some 5/16 gas line in a cheap bulkhead style.

I drilled holes large enough for the gas line & ran the length of line I wanted (I actually used pre-existing holes that just required slight reaming to be the correct size). I put rubber line over the airline everywhere I though it would contact metal. Then on each side of the c.member sheetmetal, I used large stainless nuts that have an ID that's close to the rubber hose's OD that I thread down on the rubber.

On the un-seen side (hidden in the crossmember), I threaded a nut on the hose until there was enough hose exposed to equal the thickness of the c.member steel plus a second nut.

On the exposed side, I threaded a second nut on the hose until the rubber was just flush w/the end of the nut. On the other side, I snugged the nut up against the c.member & that keeps the rubber hose from going anywhere.

I routed the drivers side airline over to the pass side where they go through different holes in the c.member & join together to the rear of the truck. Where the airline is routed through (in the c.member), I secured it w/some nylon wrapped steel adel clamps.