Vince, the EUN is an Engine Unit Number. When you look at the front of the block, just above the two-letter engine code, you will find a 6-digit number beginning with 4. See if you can find the same number on your build sheet. When you do, please post. This is another way that people can determine the provenance of a particular car's engine as the EUN wold fall into a certain range. This will help others know "about" where an EUN from this era car should fall.
The Big Human