FWIW -
While in college I worked for a retailer that sold, among other things, bicycles. For a 3 year period, I was the sole party who received, unpackaged, assembled, prepared for sale, and subsequently serviced and repaired ALL the bicycles for this establishment. Now, these were not 1938 Shelbys, nor were they 1949 Schwinns, but they were the products of 2 major US bicycle manufacturers. I can state, without reservation or hesitation, that the products shipped were not all identical or uniform. There WERE occaisional deviations from the "norm" or "standard". It is a fact that our manufacturers had intentionally or unintentionally substituted components that were different, but still functional. We put them on the floor and sold them... we did not "call the authorities"...
I believe that no one, not even Mr. Schwinn himself, can say with absolute certainty that something never happened. I do believe also, that this explanation (or excuse) is way over-used to cover-up dis-honest or unknowing deficiencies.