'99 CV S model fuel pump replacement

Need to replace fuel pump due to stuck open check valve caused by dirt that entered tank due to fill pipe rotting off at the neck. As I'm looking under the car at the top of the tank straps, there appears to be a nut on a stud, and also looks like there is a j-nut up behind the sheetmetal. Is the nut attached to the stud so they come out as one piece? What are my chances of removing this hardware without it breaking (I live in MI where lots of salt is used on the roads in winter so the hardware appears to be somewhat rusted)? Is it possible to remove the sending unit without pulling the tank? Don't think that I'll be able to get away with that shortcut if it is possible as I need to remove whatever dirt there is on the bottom of the tank. Any/all suggestions/advice will be greatly appreciated. Thanks for your time and consideration.

Go to this website:

http://www.fordparts.com/Default.aspx

You will be able to view many of the assemblies on the cars. Most fuel tanks have a locking nut on top, a brace (usually the car itself), the strap to hold the tank, and then a nut at the bottom. The two nuts may be connected with a j-bolt or a stud, depending on the vehicle.

Spray down the nut area with some kind of rust buster like WD-40 at least three times on different days, like AM of one, then the afternoon, and finally the next morning to let them soak. Finally spray the area down again before you start to work and remove the nuts.