It is most likely on the engine. That was pretty common back then, thats where mine is on the front drivers side of the engine just behind the water pump on the side of the block. All numbers no letters, stamped by hand.
Hey, thanks for the replies. I foung the two holes on the pass. side where the plate was. The engine is a 1950 235 according to the serial and casting numbers. Ive abandoned this project in pursuit of another one. The truck is on ebay now.