I have a 506 block, 1255506, E148. Figured it to be made May 14th, 1998. The code I'm referring to is actually not stamped but appears to be etched in in the block. Up front on left head bank next to the Inj Pump PMD. Reads YDD 05 27 J8. I figure the 05 27 refers to May 27th.

So what is the YDD and J8?

Thanks