88 Mustang Rust On Frame Rail Below Left Shock Tower

I've had to do it with a couple of old Fox's that had this same issue. It's a pain in the ass, but it's also necessary. Get a straight edge on the inside rails before you go welding things up solid, clean it up well and have at it.

Another note of concern though....if the rust is that bad there, it's usually bad in other places as well. Before sinking any money into it, I'd look the car over really well first (floor pans, under the rear seat, quarter panel area, firewall, etc) for more rust and rot.

You may find out that this car is better suited as a donor and not a driver.