If you have dangerous exhaust fumes coming into the car there are areas you can check in addition to fixing rust holes. If you don't have rust here are the other places you need to look to address the issue.
There are a few places you can look at in the rear of the car. One place is tail light seals and the other is filler pipe to trunk floor seal. You can also check the condition of your weather stripping for the hatch or trunk.
If you already have the fuel tank removed now is the perfect time to check the condition of the filler pipe to trunk floor seal.
Since I pulled the tank to replace the sending unit and to weld in the rear non existent tail pipe mounts, now was a perfect time to inspect things.
you can see from these photos that the seal is no longer tight against the filler neck and needs replacement.
This is the new seal that I purchased from Late Model Restoration.
To do this job you will need to loosen up the interior plastic panels in the passenger side quarter section and remove the rear pieces inside the trunk that hide the tail light electrical.
It's not badly priced and if you already have the car apart now is the time to address the safety issues.
I provided a link to their site for the part I used.
