I have two new Delco batteries and the code reading methods I have seen don't seem to work. there is an etched number in the top 7MKD27, then there is a sticker P0585 with group number on the sticker also.
The P0585 would be the date code. It really doesn't make sense, though. According to this ACDelco PDF, the P0585 indicates this battery was made in either May of 2008 or May of 2018 (05=Month; 8=Year; 5=Manufacturing plant). If these truly are brand new batteries and not 10 years old, then I'd say ACDelco is jumping the gun a little bit with their manufacture date, but it does extend the life of their warranty (which is also talked about in the PDF).