what do they mean???

No harm no foul is what I say. Better to error on the side of caution.

Hummm, did you post this twice? Once with a picture?

Look at the drivers side of the block for casting numbers. Those under the cylinder head are stamped in numbers. I forget what they mean and I'm not sitting nextr to my books.

(This was a drive by posting, gotta get my *** in gear for the overnight shift......)