I gently tapped the ring loose with a dead blow hammer and round wood dowel.

I prefer tilting up the cargo box of the pickup to a 45 degree angle instead of dropping the tank.
Loosen half the bolts, remove the others, watch that you do not pinch the electrical wires at the back near the license plate. If alone, jack up the cargo box and use jack stands and timbers to safely hold it. I had to jack mine up alone in the 40 mph gusts of tropical storm Ernesto.

What you need to pay special attention to is the “roll over valve.”
The roll over valve is hard to remove without breaking,
and the replacement tank generally does not give you a new one.
Many parts stores will have to special order one if you break your original.

I took a Dremel tool and slowly and carefully cut away the old tank parts from the roll over valve to leave it undamaged for re-use.

Do not let a squirrel or rodent gnaw a hole in the fuel line attachment Elbow to the pump assembly.
Do not ask me how I know this.