I assume you have owned it since new? How many miles when you bought it? Could the dealer have wrecked it and repaired it, not disclosing the damage? (Can you say LAWSUIT?)(I know a guy that had a Malibu, he had owned since new. Had a very minor fender bender after a couple years. Took it to the body shop, and his friend asked, "when did you wreck it before?" Um NEVER he said, found out the dealer had crunched it, he got about 2K back on it. ) Sorry to Digress, Anyway Ford would not "Splice" anything in a frame while building it. They would just scrap the frame out if something was discovered while building the truck, and start another one. (I have seen 1/2 built GM vans scrapped because they got damaged while building, or some manufacturing defect was discovered too late, (missed spot welds, ect...)
If what your body shop sees is possibly the normal design, and they don't know that, then do they know what THEY Are doing?