Thanks guys!
I didn't look under the car, that would have been the next step had the car been dry. The cowl in front of the windshield had a heavy coat of paint on both sides and there was heavy texture evident inside. The undercoating was so thick and heavy that any cutwork would be hidden. It looked like it was applied with a trowel. I will not buy a mustang if I cannot inspect the subframe. At first glance it looked good, but fell apart in a hurry.
The best mustangs are the ones that don't look good, torn seats, bumps and bruises, warped dash, headliner falling, and the seller wants top dollar and most buyers pass, except me. Two of the last three we acquired have original date coded radiators, tight suspensions and steering and brakes, no undercoating and the only rust is on the 65 and 68 fastbacks, a tiny bubble on the front lower door and the inside forward lower door seam, the 68 has mud in the lower rear quarters, the rest of both car body's are dry as a bone. One way to spot a dry mustang from 10 feet away is the door panels. If they have been replaced or the originals are warped, it's wet. Every Mustang we acquired have the original dry flat door panels and carpet.