Welcome to NYM, nice looking II. Everyone with newer Mustangs then the 74-78 Mustang II's if it was'nt for the Mustang II's you would'nt be driving a Mustang now.
Welcome to NYM Brian, check your grounds, sounds like you may have a bad one. Try posting this question in the classic Mustang section, you might get some other suggestions. Oh & BTW nice to have another classic Stang here.:awesomework:
Its what keeps happening with older cars, you start digging & you usually keep finding more rust. That is why with a 65 Fastback & a 69 Coupe I am STILL doing rust repair.