Paint markings on 1997 5.9 litre

Sorry but I am new to this. While recently changing my oil I noticed hand painted letters on the engine block of my 1997 Ram 1500, 5.9 litre engine. Is this normal on a factory engine?

Yes, it was used back in the 60's as well. This picture was posted in another thread.

Its the variation in bore size from the factory.