I decided to go ahead
with replacing my very dead Group 31 AGM batteries with LiFePO4 batteries
of the same size. I contacted Smartbattery.com and they were very
responsive to all my questions. They weren't the very cheapest I
found on the Internet but they seemed to be one of the few who have a
clear business and support their product. After a couple of days, I
got handed off to their distributor in North Carolina who was also
very responsive to all my questions and who went the extra mile in
finding the correct answer for me and my specific set up. When I
ordered them, I called the guy and gave him my credit card number on
a Friday afternoon. I told him I didn’t need instant service and
could wait until Monday. He had a different person call me for the
details and I got the call back by 4pm which was too late for them to
go out that day. But they went out on Monday and I got them via UPS
on the following Wednesday. Very fast delivery.