The passenger side front frame rail, just forward of the floor support had rust but thankfully I was able to cut it out and fabricate a small repair panel out of some spare steel.
After I cut out the rust I also had to scrape off the old underseal which is a messy job, made a little easier because the headers are off the car at present.
After a few spot welds I plug welded each side, ground the welds down and called the job done 🙂
I will coat the area with underseal though 🙂
My Mustang Journey 