Anyone familiar with Dart Swingers knows that it has several vulnerable rust areas including the trunk floor pans and the frame rails. These areas must either be cut out and repaired or completely replaced. I purchased new trunk pans and trunk extensions to fix this. You will need to cut out the hole for the fuel tank filler tube and also install new fuel tank support brackets and spare tire hold down flange. The pans come in two pieces so you can get them into the trunk cavity. These pans are a bit of a pain to line up and join and the metal is quite thin and easily burn through when welding. Visit this internet hot link for additional trunk floor installation information.