RE: Group 41 Batteries at Costco
My local Costco (Shorline area, North Seattle) no longer stocks or list the
Group 41, I checked just recently.  But when my starting battery went away
in the middle of a trip last fall I had no problem getting one at a
Wallmart, with similar warranty.  And don't flame me for dealing with
Wallmart, they were the best choice at the time, both availability and
price.
BTW, talking about warranty, when looking for a new battery for my other
vehicle a couple of months ago I noticed that Auto Zone had the best
warranty and best online reference information.  A little more expensive but
warranty longer than any place else.