Newbie could use some fuel system help

[justjoef]

Hi Folks.... New kid on the block (at least on this site)

I'm hoping someone can help with the fuel tank sending unit for my truck. It's pouring rain today and I'm trying to order parts for repairs. Pretty much everything looks to be original and is rusted out. The tank and feed/return lines are already on order. Rather than crawl under the truck in the rain to trace the other line(s) I thought someone could definitively define the ports on the photo below. I'm thinking vent?, feed, return, and maybe charcoal canister? Thanks for any feedback.