On the 1961, the serial number is stamped into the top of the left frame rail in two spots.
First location is in the engine compartment. (With the hood open)Look on top of frame rail area located between the driver front wheel and the exhaust manifold.
Second location is on the same frame rail located under the cab. It would be about directly below the gas tank area if you removed the cab.
The "serial number" stamped into the frame is only part of the total VIN number. The last seven digits of VIN i.e. K100001.
