SOURCE- 1963 Model YearThe frames on the 427 cars were the standard big block assemblies with one notable exception. The factory lightweights carried a special frame tag located under the radiator support mounting bracket.
This tag carried a part number, C3AA-5005-AA MOD.
Ford discontinued the stamping of the VIN number on the frames starting with the 1963 model year.
Thank you.SOURCE- 1963 Model Year