What day was cougar 500001 built?
actual build date = 09/07/66
Thanks Jim! That’s what I needed. the actual build date!
I am sure that was the recorded build date, as that was the first day any Cougars were recorded as being built,being serialized, and also the first day that the line was running production Cougars. I suspect that it was actually bucked and built far earlier than that. Most pre production show units are built as prototypes on a pilot production line. I want to qualify that I don’t have specific knowledge of what happened on that day with Cougar 1. I do know it was the first day of actual production on the assembly line. The additional prep work to create an Introductory Show Unit would have required the car to have been started much earlier.
Keep in mind that on August 2nd of 1966 (more than a month before the first “build” date) a Cougar was shown to “newsmen” and a group of dealers on St. Thomas Island. At least a some pilot production had occurred by that time. The St. Thomas Cougar was said to have been a bit rough, but it also appears that it could have been the same car later used for the initial Cougars ads with the white Cougar.
The door tag on cougar 1 decodes as july 4th??
Yes it does, typical Ford practice for Introductory Show Unit vehicles. That is the “Scheduled” build date.
Now, I’m sure you meant to indicate '67 / Cougar 1, and everyone else seems to have picked up on that except me (LOL?). I’m gonna split hairs though, since “500001” got built more than once 
1970 = 0F91G500001, a Competition Yellow, Boss 302 Eliminator, with an invoice date of Aug 11th, 1969
LOL!! Yes, Mike 1967/ Cougar 1 !!! But that could make for another interesting question! As to the locations of the 68,69,and 70 500001’s??
There would be two each for 1968 and 1969.
San Jose and Dearborn.
San Jose and Dearborn used duplicate serial numbers?
Yes, but we’re talking serial numbers not the complete vin number, the latter includes a plant designation, therefore a unique vin number.