Fig. The eighth digit of the Vehicle Identification Number (VIN) identifies the engine. The adhesive-backed labels attached to the engine, laser etching or stampings on the engine block indicate the engine unit number/date code. All engines are stamped with a VIN derivative. The primary location of the Engine ID for the 3400 (LA1) engine is on top of the RH rocker arm cover or front of RH oil pan rail. The primary location (1) of the VIN derivative and the secondary location (2) of the VIN derivative for the 3400 (LA1) engine is above the starter motor on the engine block.