Amazing!!! For a couple of years or more, I have tried to trace a cabin full of gas fumes in my 1970 Z. I bought a cheap fuel/fume "sniffer" or detector. Even with it, I gave up, until recently I tried again inside and around the gas filler tube. The filler was/is new and tightened down very well, but fumes still escaped, heavily. I pondered and decided to buy large O rings (a 2 1/2" a 2 1/4" and a 2") from Hydraulic Service Seals and Supply here in Las Vegas. I took the gas cap mounting ring with me. I used either the 2 1/4" or 2" o ring inside the fuel door and stretched it over the lip of and around the filler tube, of course, after removing the gas cap mounting ring. I placed the 2 1/2" o ring inside the gas cap mounting ring with just a very very small dab of silicone just to hold it in place while turning the ring over to replace it. The three 5m-0.8 were too short, due to the o rings. I used 5m-0.8×20mm machine screws. After screwing them down quite snugly, I removed one screw at a time and replaced the original screws. If the new screws are left in, the bottom/lower one will be close to the filler tube. The other two are not close at all. I left the doors open overnight, to dissipate the fumes. The next day, I closed the doors and bounced the back end up and down to slouch the fuel around. Guess What? No More Gas Fumes!!! Oh yes, I had the in-hatch panel off, and any place that looked like it could escape fumes, I used a small brush and brushed on Eastwood's Brush On Seam Sealer, with care to keep as much as I could off the hoses. I hope this is clear enough to help someone. I am unable to post pictures. I am all smiles. Ernest