The vin on the radiator core support only has 6 numbers, is this normal?

I was wondering on why they did not stamp the entire vin as it's shown on the dash?

I suppose that for these secondary parts, only the serial # is sufficient to identify the vehicle.

Rad support VIN.jpg*
My core support. 145923 is the serial# of my '71 Demon (also present on the engine block, gearbox and under the package tray.
The complete VIN is only present on the fender tag, the dashboard and the passenger side inner fender.