Tim - I suspect the TF stamped ID number was the beginning of a federal program, it was definitely done by the factory on all trucks - of very many 56-58 trucks I've had / parted out, from various assembly plants, I've never seen one without it in the same place and configuration, like
this on a friends 56 panel
LONGBOX - interesting, as about 1960 the frame stamped numbers started being done double like that, bare 60's frames I've seen had them in both places, near the steering box and under the cab far enough to be invisible without careful use of a mirror - Tony [4-5-6ChevyTrucks] might be able to confirm that?
rbs56 - on a GMC look at the outside of the passenger front frame horn, might find it stamped there
Bill
