Fuel sending unit gasket

It is a newer gas tank, but the tank has been on the car for over 10 years and was sealing well for most of it’s life. Now that I have had the tank taken off and cleaned out and put back together and the gas lines cleaned out from sitting too long, gas wants to leak out of the sending unit if I put in more than 5 gallons. So, my troop ring seems to work well. I just need to get a new gasket as many of you have suggested. Yes, Rusty.