OK, looking for the replacement has enlightened me.

All the places say this should have a Group 48, and possibly some of the 47's which have enough power to meet spec. All of them are a bit smaller than this 49 and less powerful.

I plan to go with the Walmart EverStart Platinum BOXED AGM Battery, Group Size H8 / LN5 / 49 12 Volt, 900 CCA, $180 delivered.

https://www.walmart.com/ip/seort/380996471

I have had a few of their house brand batteries and found them to be good.

The smaller ones like 48 are priced the same. No downside to the 49.

Since this one is going OK at 20 YO, I am thinking that being a tad over sized/powered is a good thing for longevity and helps prevent deterioration by avoiding stress. I have always put the most battery i could stuff in my trucks because they have loads on them.