'66 Barracuda gas filler/tank

I replaced the tank on my ‘66 three weeks ago. I pulled the six screws out on the top of the tank and the three screws holding the filler tube to the quarter panel. This allowed me to twist the filler tube loose from the tank. I did NOT pull the filler tube out.
Underneath, after removing the strap holding the tank and disconnecting the fuel line, I was able to wiggle and twist the tank loose off the filler tube.
To put the new tank on, I lightly coated the end of the filler tube with Lubriplate to help wiggle the new tank onto the filler tube. Hope this helps.