First burn out as much gas as you can.
The less gas you have in it, the easier it will be. You can do it by yourself, but its easier with two people. If your going to do it by yourself, you will need a floor jack to lower the tank.
There are two straps that hold the tank up, remove the two bolts in the rear. Push the tank forward and lower it a little. There is a small ground wire that comes out of the top of the tank and hooks to the rear panel body. Remove the screw and unhook it from the body. Now reach above the tank and unhook the fuel gage sending unit. It just unplugs. Next you will need a drain pan to catch any fuel that may be in the fuel line. The fuel line is located on the drivers side. Just cut it and replace it with a new one upon installation. There are is also two other fuel lines on the passenger side. One is an emission's line and the other is a fuel return line.
Cut these too and replace them.
You are now ready to lower the tank all the way down.
Nothing to it.