My 20 cents, get the #'s off the block, problem solved.

 

ya i know if i could only find them

 

The 413 was a RB block, different intakes. The block numbers should be fairly esay to find, drivers side of the block, towards the back half ways up! But even that may still not tell you the year of the block, as they used the same casting #2568130 for 12 years on 383 blocks,