Ok I had hoped my first post wasn't a stupid question but it is what it is. I have a gen 4 5.3 engine and found these markings in the lifter valley. Do they mean anything that I need to know?

I did a search and didn't come up with anything. I'm sure I'll have more dumb questions soon.

It will not allow me to add a picture.

So it says

A10
9-18
40

Written by what looks like a paint pen.