I would also supplement using the BMHT with production data, cars on registry prior and after and see if they align- The BMHT sent me the wrong engine number on a cert (which I didn't notice until I found my engine tag -a 26D engine - and began researching the numbers correctness of my car) - good news was on the car the Engine tag, VIN and Body number and numbers on the surround all match. When I paid the 9 bucks to ask a researcher - they agreed they made an error (like 14 years ago) and sent me a corrected cert. I knew the cert was wrong since the production date was 4 months after the last 1C engine was used.