I found this REAL one... It's labeled Dearborn Pilot Plant..
Updated: 11/5/2016 - I found some more info on the pic below. It is from a Dearborn Pre-Production "Prototype" Convertible, VIN# 5S08F100009 - And Yes, The "S" is correct for the 2nd digit in the VIN#. Some Dearborn Prototype cars had the "S" 2nd digit in the VIN as well. I think Bob Fria's book covers this in depth.
See Below: