These threads are intriguing to follow and shed light on a myriad of activities coordinating owner, dealer, orders, bookkeeping, parts inventory, manufacturing, assembly, inspection and transit to the purchaser.
I have paperwork from a 1968 ordered 6 26 67 with an order # 109529. SPD on tag is 929 and a "tentative" invoice dated 9 22 67. A second "firm" invoice is dated 10 27 67 has a slight price adjustment of some options . Broadcast sheet is not available. This was a St Louis car.
Original owner says there was a delay in delivery by lack of some parts availibility. The order form has a second hand written date 10 12 67. I have no means to verify if that is the day the car was complete, and no way to know why the firm date is several days after the spd and the tentative invoice date.
I agree the metal tag was conducive to fabrication durability. I've seen reports the tag was originally wired to the firewall windshield component at the body was fabricated and moved to the inner fender after body in white was complete. Was this when the inspector stamp was punched? and tag bent up just prior to coat and paint? Undoubtedly (more than one?) broadcast sheets were scattered about the car (almost certainly after paint (I've never seen one with primer or body color paint overspray) and how did so many get mixed up about cars without creating errors is surprising.
There was certainly a lot of variables as "fleet cars" and "special packages" were run and then then the cars built to purchaser spec were certainly watched over to reduce errors.