All similar vintage small blocks share the same outward appearances, 340 engine colors varied through the years they were offered. The casting numbers are on the side of the block and clearly say "340" but won't be of much help if you don't crawl under the cars, if the paint on the engine is not too heavy there are assembly numbers stamped into the front of the block just under the drivers side head that will tell you which displacement the engine was when new. To what level do you judge these cars?