On the '60-'66 Chevy light-duty trucks, the only location you will find the VIN is on the top of the driver side frame rail, adjacent to the exhaust manifold, near the engine perch. It will only be the last seven alpha-numeric characters of the VIN. It will begin with a letter, which signifies the production plant.
The GMC trucks of the same years did not have the VIN or any portion of it, stamped on the frame.