There was a Ford Dealer in Coral Gables(Miami) Fl. Apparently they ordered a group of 66 Mustang Convertible in Signal Flare Red with black interiors. Ended up with two that were 4 digits apart. Later found another one that came from Deel but it's number was a couple thousand away. They were a high volume dealer and the sales manager or whoever ordered, had a penchant for that color and equip. They were all with AT, PS. C Code with AC. Possibly, these cars could have started out as rentals as they big in that. During that time frame, early to mid 80's, it was pretty easy to find 66 Mustang cvts-the most common of all the early Mustang cvts.
One of those 4 digit ones, sat on a concrete driveway at a private residence, for years. A Miami car, new from, Deel, it was totally rotted underneath from front to back. Be willing to bet it saw some beach travel! Bought it for parts.