I called AC Delco before and after being refused the free replacement by the dealer where it was bought and asked if there was another place to get the free warranty replacement (another dealer or store) and I was told that it was unlikely that another dealer would make good on someone else's sale but I could try.
I tested the lead acid replacement in Walmart today and the CCA was significantly above the 730 CCA rating and it was dated this month so I took it home. And just $5 core charge.
My 3 year old Delco, rated at 770 CCA tested at about 480 on mu tester. I (now) suspect it was an outdated battery when I bought it.