This is only the 2nd time I've had the water pump off in 40+ years but the first time I noticed the hole in the bottom (see pic). I think the pump may be a replacement cause there's no grease zerk on top ( or even a place for one) that all the illustrations I've seen show on an original. Not concerned about it cause it's obvously there for a reason, I just don't know what that is. Is it to shoot some sort of lube into the pump? Should there be a plug of some type in it that's gone missing? It's not threaded.