drain tank... break lugnuts loose... jack up drivers side of car (rear)... place jack stands under car... remove tire and rim... unplug sending unit plug... use drift (screwdriver) to remove sending unit lock ring... remove sending unit...
Go buy a cheap electric fuel pump to drain the gas. You will still lose some gas but it will help a lot.
if you ever have the tank out...have a drain plug installed. an oil pan repair plug is what I use... not mine but gives you an idea of what it would look like...
I like the Mustang style tanks with a drain plug. Tanks without a drain, I put a little compressed air into the tank to pressurize it and push the fuel out the fuel line into a gas can. I use a blowgun at the filler pipe and seal it with a piece of rubber gasket material that has a small hole in it for the blowgun. Very low pressure is enough - don't want to distort the tank. Once upon a time I had the special tool made for removing the retaining ring. But I found a few taps with a hammer and a bigger punch will spin them right off. The retaining ring should come loose pretty easy if it was installed correctly. I have seen many backyard installs that used Permatex #2 (the hardening one) and that can make the old one tough to remove. If the ring gets damaged, get a new one. They are easy to damage if beat on. I use a little gasket high tack in the tanks groove to make sure the o-ring stays put during assembly.
I put grease on the gasket and ring before install, it seems to go on smoother. I think most new sending units come with a new gasket and ring.
I forgot about the vapor return line (if your tank has one). Need to plug that when doing the pressure thing to drain the tank.
they make a wrench for the ring, i picked one up. works awesome. i replaced mine once just laying on the ground, no, jack, tire off, or anything like that. one of the simplest replacements.