To throw another iron into the fire, I watched, over a several week period, as a '69 Mustang was delivered, brand new, to the Exec Garage in the southwest corner of T&C Livonia, stripped down, and turned into a full-on Trans-AM SCCA Boss. The body work was done (the cut-in scoops in the rear quarters were not used in the Boss cars, so they were filled.)
If I remember correctly, an engine came in on a pallet with markings showing it came from Bud Moore.
It came in as a brand new car. It went out as a brand new car, as well. But it went away as a fully done-up road racer, and it was all done on FMoCo property by Ford employees. I have no idea what the vin tags said. As I remember, that car was destroyed, and the driver killed in an SCCA race of the 'round-the-houses' sort. It happened on Wide Track Drive in Pontiac a few months after the car was finished.
And we haven't even mentioned the facility over on the edge of Melvindale where they did the years-ahead planning of assembly lines. They had a large store of cars there that had been modified to be used in the planning. If you knew who to talk to, it was entirely possible to get a 'dollar' car there to be turned into some sort of competition vehicle. I personally participated in two such activities---showing up with a roll-back truck in one instance and a pick-up and trailer the other time.
All sorts of things were possible if you knew who to ask.
KS