When did the format change on the rear leaf spring stamped numbers occur? The earlier version have the C4ZA and 5556S on separate lines while later springs combine both into one line. See pictures.
Some of the Shelby gurus may have your answer. Perhaps a survey would help determine the time frame. 6S281 which was built at Ford in mid October 65 has the type of stamping in the picture. By the way, if anybody has one stamped spring that matches this one I am extremely interested in buying it. Thank you
Of course the change over would be a date for the supplier and not a specific car. You may be in the range with just these two examples since they were made only 29 days apart. Or their may have been multiple machines using both formats running at the same time or for a period of time
Jeff:Thank you, as always a very credible source of accurate information. Objective without speculation or agenda.
Just pointing out a few things I noticed. Will look to see if I have any examples with in that date gap.
And thanks for the kind comments but FAR from perfect or from never making a mistake. Just glad to help from time to time help determine what may have taken place or happened concerning the cars we all enjoy