A 46 Chevrolet 1/2 ton pick up or most anything from that era didn't have a VIN per say.
Most titles were issued with the engine number on the title. Occasionally, the production number was used. The engine number is on the right side of the engine behind the distributor on a flat smooth surface of the block. The production number was on the right hand side of the cowl, right around the corner from the fire wall just under the hood about halfway between the top and the bottom of the cowl so that it would be covered when the hood was closed. The better choice for a VIN type of number is the production number. It tells more about the vehicle and it has a better chance of remaining with the vehicle through it's life. In most states, the number on the title was dictated by the state and, for some reason, the engine numbers were used.
Joe
