These 6s in the OP, which I believe are Deka GC15s, each have an English/French sticker on top which says in English, "Ship Code M19, Recharge by 06/20" Another sticker down low on the end says 11/19, which is usually the build date AFAIK. No code stamped in the post like a Trojan, eg.
The markings on their cases say:
93081G16 0877 and on the other
93081C1E 0681 Hard to read G vs C, so not sure there.
Mex said in a post some years ago, "The brand into the lid shows which facility and which line and date that battery came off of, very similar to a batch #. "
Rolls has its own system for batch numbers
https://www.rollsbattery.com/wp-content/uploads/2019/11/Rolls-Battery-Date-Code.pdfAnother sticker on them says, "Filled with acid UN 2794" That would be a UN regulation for Wets. Lithium has another number, eg.
https://www.gwp.co.uk/guides/un3480-regulations/#labellingInterstate says here they have their own date code stamped on to start with, then the local dealer will recharge them after three months and put a sticker on them. Their U-batts have the US Battery system which is the letter number and a last letter for the plant location.
https://bumpertobumperradio.com/latest-news/item/929-how-can-i-tell-the-age-of-my-car-battery-interstate-batteries