"My absolute favorite thing from them is the Diehard series of batteries. They have served my vehicles well, and I'm hoping they don't disappear."
Not to bust your bubble, but Sears doesn't make their own DieHard batteries, and never has. The good ones over the years have been made by Johnson Controls, which is one of the biggest battery manufacturers in the world. They do make a good quality battery. For a period of time Exide made the DieHards and they were of a lower quality.
The EverStart brand (marketed by Walmart) is also made by Johnson Controls. I just had to replace an EverStart Maxx (higher capacity) battery in my wife's 2003 Saab 9-3 Vector in the past month. It wouldn't hold a full charge anymore, and would discharge to 12.4V overnight with only the normal 9 ma parasitic drain. When I took the battery out I found that I had fastened the original receipt to the side of it in a plastic bag. The receipt was dated 2009, so that battery had endured 8 years of New England winters. I called that good. And, I had paid less than $80 for it. Cost me $118, for another one. Battery prices have gone up over the past decade.