I am often amused by antique car owners who are certain that some part or feature of their car is absolutely authentic and original, and has never been apart, changed, repaired etc. They are quite certain because they 'know' the history of their car all the way back to '37 when uncle Joe traded a milk cow for it.
In actual fact, cars were serviced commencing almost immediately after the sale, and the work extended to major repairs on seemingly new cars, not just adding water to the battery.
Ford Motor Company itself was one of the biggest promoters of selling service work, accessories, and replacement parts, not to mention the thousands of independent garages and parts houses like Western Auto, and legions of mechanics ready to lay a wrench on your car.
Think about the Ford Service Bulletins and the continuous flow of information and feedback regarding parts being changed out on cars almost as soon as they were out of the showroom. This work was really being done, and on a big scale! How many cars escaped this fate?
It was very common practice for cars to be brought to dealers and garages where things were repaired, rebuilt, or replaced, whether they really needed it or not.
Despite your strongest held beliefs, what are the chances that some detail of your car is really factory original, especially if it defies the researched history of Ford design changes and production change implementation?