What year are my catamaran D4BB Diesel Engines?
 

I have two D4BB Hyundai diesel engines marinized by Craftsman Marine in our catamaran. We are trying to import her but the EPA wants the engines certified. Anyone know how to find the year these engines were manufactured?
Here is the serial number on the side: 23120514
https://cimg4.ibsrv.net/gimg/www.hyu...9c6f3fb8b5.jpg
https://cimg3.ibsrv.net/gimg/www.hyu...f78a6a50a7.jpg
Here is Stella Maris at anchor.