Would it be reasonable to assume that several different stamping machine were used to stamp the same part? with nearly 680k mustangs produced in 1965 i find it hard to imagine one machine stamped every single left front fender apron for example. There must have been dozens of machines stamping the same part, and possibly in several different locations, and therefore different stamps on the same part, after all we see different dates on the same car, so why not different stamps ?