solved!
i put 3 fiberglass coats, and then fiber glass jelly bondo

before




after




i reinforced the back with 20 gauge metal and clean up the rust and sprayed on rust controll, then rust oleum

 

What an odd place to rust.

 

the ppl that had the car b4 me. didnt know how to take care of stuff and did crap jobs on it.

 

not an odd place for rust, but it takes a long time for it to get there. It starts on the lip inside the wheel well where the quarter connects to the frame, slowly rotts that and works its way into the car. I has rust starting there, it was just getting into the car, nothing anywhere near what you have but it was starting. I cut the heavy stuff out years ago and just used some heavy rubber insulating compound to cover the bare metal, then just recently chopped it all out when i did my mini tub job.

I hope you cut all the rust out and at least painted the bare metal before glassing over it. It can still come back it you didnt