rear quarter patch panel replacement for my TA

[WS6]

thanks for the tips. i have this stuff called ospho that will convert rust to a phosphate primer basically. ive used this before and have been pleased. i sand the area down as best as possible first. definetly want to get rid of the heavy stuff. i then just wipe the panel down or brush it down with ospho and let it dry for a day. i dont know what it would do to the area being welded or painted over with auto paint. i know spray paint is no big deal. it covers it right up. i would only use the ospho on the inside which is where the rust starts and is anyway. thanks