I understand exactly what was occuring to the OP and the fuel tank seal.

I was responding to the poster directly ahead of me -- see the quote in my posts -- who appeared to be claiming that excess gasoline put into a normal tank after the first clickoffs somehow was "lost" and "sloshed" away.

I also did not understand how the hoses "let any excess gas to drain."

For convenience, here is the original post to which I was replying:
"There is a reason that gas pumps automatically stop pumping. They are designed so that you don't overfill your tank, which sounds like what you did. Topping off a tank is a waste of money and I don't recommend it, instead just send me your extra cash. That extra gas you put in sloshes around and is ultimately lost as you drive down the road. Most filler hoses are designed to let any excess gas to drain."

My response was not to you, it was to the previous post from dancssei. His comments about excess gas draining to the road were incorrect. Your comments were accurate.

I'm glad you fixed it, but considering you clamped the assembly down with a lot of crud on the sealing surfaces you have probably damaged the O ring. A new retainer ring is certainly optional, but I would never do this repair without putting a new O ring in. Something about gas leaks makes me nervous.

The O-ring is a pretty stout peice of rubber. It came out looking like new, no crimps or deformation of any sort. It was still very pliable, so it wasn't like aged rubber at all. It fits down in a channel on the top of the tank, and upon inspection it was clear it would seal up just fine. If there were any question at all, I would have replaced it.

TBH, when I changed the sender and put everything back together I didn't even notice the O-ring, nor did I take any care at all to remove all the debris because I was nervous about getting the crud in the tank. First time I'd pulled a pump, so I chalk it up to inexperience and nothing more.

Thank you for responding. I apologize that I mistook the response to be for me.

I have this fuel gauge sender repair to do to my 03 leSabre and I am reading carefully what experiences everyone is having doing their own.