The main tanks have a 3/4 tube that runs through them to allow
the auxilary fuel lines to pass through.
On welded tanks these are welded at the tank ends, but on my
pro sealed tanks I needed a way to attach them.
I've made a screw flange out of a tubing clamp collar and drill
and tapped it for small machine screws.
I had to move the fitting for the vent over as I had them in line
with the pass thru tubing.