Rust'in in NH
I should have posted a follow up to my original post here back in 2008. Its good insight into what happens when you observe fuel leakage anywhere near the fuel tank.
Basically, in my case, rust overtook the sending unit and part of the tank. It turns out however that fuel leakage, as serious an issue as it was, was really only a small part of my issue back then. Water intrusion into the tank managed to take out the injection pump in a big way. Its amazing that the truck still ran, and testimoney to what sort of loose tolerance the pump will take and still function OK. Sent the core down to RDS. Said it was the worst he'd ever seen. Not even worth a core. Hearing this I checked the injectors. For what ever reason two were fine, but two were also junk.
Moral of the story - if you see fuel leaks of any kind, fix the issue right away. It should be said my truck is a bone stick 1995 ROW truck, now converted to LHD and going thru finishing stages of restoration. So start with a proper sending unit thats vented at the tank, use POR or Zero-Rust or the like on the sending unit and tape off the fuel line nipples before spraying. With the proper connections in place and a tank with no rust holes, you should be on your way