it's generally said the frame stamped number started with the 55 2nd, but as Tim notes, documentation doesn't state it until 58, I believe it varied at different plants .... having seen quite a few of the TF series trucks, '56 up years have always had the frame numbers,
here is a pic of a '56 showing the format [from the Oakland plant]
4brads - the leading model designation was never used on the frame any of the TF years
Bill
