I have a 1967 Belvedere and had to change the gas tank so I Bought a repo and installed it leaked around the filler tube at the tank , so I found a good original and installed it leaked in the same place. I replaced the rubber grommit both times what is the secret.

Thanks Joe

Is the replacement tank inlet the correct dimension? are you using hose clamps? I replaced mine last year with a good used stock mopar tank, and had no issues. It seems about as straight forward as can be, don't know where any "secrets" could hide???

Thanks for the reply , I used a repo tank and an original it seems to be leaking around the filler tube at the tank.I did use hose clamps where the rubber elbo fits on the metal filler tube.I also used new rubber gromets each time I tried a different tank.Is the j-hook where you get the tank level or am I missing something?

Make sure the filler tube is clean on the outside and use grease to slide it all the way into the tank. Sometimes the crud will let gas seep by on the filler tube.

Like it says above, make sure the tube is clean and smooth. I spray the tube with silicone and insert..

Thanks for the rplies fella's I did clean the tube well and used both grease and baby oil.Any body live close to Mobile Alabama lol

Too much lube will often compromise a good seal between the gasket and the steel and offer the fuel a path to escape. Part of the reason they use rubber is because it seals and contours somewhat to rough uneven surfaces. Also, in case I missed something, use a new seal, the originals can get hard and quit working.

By seal do you mean the rubber grommet that fits in the mouth of the tank it's self , if so who sells a good one? I have replaced this when I Changed to a different tank , when the tank doesn't leak I can't get the bolt that holds the metal filler tube in the frame it is miss aligned.

Yes, the big donut seal that fits into the tank. You are correct, if the tube is not passing through it at the designed angle it could "pry" it into a possition that causes a gap/leak.