There is not a quick external check. The block casting number, over the oil filter and below the block head line, is a semi decent method. If the number starts with ECK, it is not a 312. If the number starts with EDB, it is probably 292 with a very small chance of it being a 312. If there are not three capital letters starting the number, it is not a 312 and is probably a later 292, around 1959. If the casting number is ECZ, you have about an 80% chance it is a 312, but it could be a 292.What engine is in my car, block # ECZ 6015?