HGST Ultrastar 7K4000 manufactured date?

I was under the impression that these were discontinued drives but bought two new ones on Amazon and they have MAR-2018 dates on them. HGST labeling doesn’t make sense to me but they have two different ids labeled as P/N: 0F14688 and H3U40006472S

The HGST site has them listed as EOL Ultrastar 7K4000. I assume EOL means End of Life, so am confused about the 2018 manufactured dates.

Were these really still being manufactured by HGST (WD?) in 2018?

Also, I can’t find where to register them. With a 5 year warranty I don’t want to be searching for an old receipt (that doesn’t even have the serial numbers on it) years from now if needed.