1967 Dart trunk area floor pan question

The upper piece that's rusted out is the back part of the transition pan just forward of the trunk floor. Your best bet is to patch it if you can. It's a hell of a job to replace it.
Thanks for the advice. Yeah, I’ll have to try to patch it. I’m not going to replace everything there since everything else is perfectly solid.

I’ll cut out the bad sheet metal this weekend,
see what I have to work this. Then I’ll try to fabricate some patches out of spare sheet metal I have.