How to change the plastic fitting at the end of the waterline on a toilet?

Question

you know the one that hooks to the flush valve or ballcock. I'm replacing the ballcock and I want to use the newer plastic fitting as opposed to the older one. I just don't know how to remove the old plastic fitting. thanks

Answer 1

I see that hmicda asked a question and left, and you answered, but I don't see that hmicda came back to give you an answer.

I think that you should be able to unscrew the old plastic nut holding the threaded ending of the old plastic piping water-tight to the bottom of the tank of the toilet; and then replace that with the new plastic threaded ending of the new tube; a new sealing washer; and the new plastic nut. eh?

Answer 2

Is this the plastic nut that holds the supply line to the plastic threads that are protruding through the tank (towards the floor)?