I had the same problem when I got my new tank from American Classic. I cut the vent tube down and used a longer hose to connect it to the filler. I tried to bend it but it was going to require to much pressure. Don't recall a problem with metric. Got a new sending unit at the time also, still haven't got that thing working. Can the gauge on the dash burn out or ware out?
I will say I am having a lot of fun drive the truck around town now.