It takes me 16 hours at least to appraise a mustang for a client, most of that time is research and viewing the videotapes. I will find that the car is honest or a remade pig.
The cars tell a story but you have to dig and after a while, the whole picture becomes clear. Date codes on the glass and other parts is important. The hardest part is finding accident damage because those Ford Dealer trained body men knew their stuff and had good parts. I count welds and their locations on the floor pan on the video, some sellers put small dents and dings to make it look factory.
I don't know why a few body plugs are missing on honest cars, I assume the factory didn't install them.