Engine bearing markings?

The back of the main bearings on one of my big blocks are all marked with 001, along with some letters. Does that mean they are .001" oversize? They appear to be the factory originals but I'm not sure of this. If the above is true, are replacements hard to find? Thanks!

It is not unusual to have one or more oversize bearings. It meant that the standard bearing would have had too much clearance on that journal. Is you block stamped with a malteze cross?