Recent colder weather accelerated the end of the battery's life. The Interstate H8 lasted well over 6 years but was really struggling to start in the colder mornings. While in Home Depot I saw they had racks of batteries near the exit, Exide brand. They had the proper H8 group size, with good specs: 950 CCA, 170 minutes reserve capacity. $119 + $12 core charge.
https://www.homedepot.com/p/Exide-SP...-308488577-_-N
We'll see how long this one lasts.