filler doohickey will be here tomorrow. Took them near a week to ship it, but $65 shipped instead of $80 plus shipping from anywhere else I can survive.
Haven't touched the tank aside from taking it back out.
I had another thought on position. If I wrap a hauler bed around it later, I'm going to want the tall part against the cab. and if I put the fitting over the existing stack hole it might be right against the stock fuel tank when flipped around; I need to look at that.
and think harder about building that bed before the right side of mine vacates