L K under the rear arches they rot real bad there, usually between bumper and the body hav a real good look and poke around cuz road dirt can cover it up, can rust around the filler cap, chassis rails and check under the side skirts as they trap water and rot the sills! looka around the window seals and around the sunroof if spots of rust are appearing its more than likely its rotting inside out, u may think u can rub the outside down and get rid of it but if its started from underneth the panels its terminal! Ive recently bought one but had a look at a good handful and most wer rotten! unfortuately its something most of us ford owners got too deal with