Want to save the Die Hard? Here's how. If you want to be all greenie about it, dump the electrolyte in something and dispose of it properly......however that is. Or you can just dump it out in the dirt.
Then, rinse it out with a garden hose and a strong nozzle. Wear eye protection. Rinse it until it stops puking out crap and the water is CLEAN. Then drain it of all the water. Now, go to your local O'Reilly (see how I worked that plug in?) and buy some fresh battery acid. It comes in a six quart container and it's CHEAP. Refill the battery and slow charge it overnight. It will likely last another ten years. My best friend has one Daddy bought new in about 1974 "or so". I did the above procedure to it when I got it from Daddy in 1982 "or so". Then I emptied it out and gave it to my best friend about 1995 "or so". It was still good. It still is good. He keeps it on his work bench as a decoration because it was made with colored plastic and it looks super cool. No stickers. I guarantee you he could refill it charge it up tomorrow and it would still be good. They go bad from all the crap and mineral buildup from over the years. If you flush that out before the battery completely dies, you have a very good chance to save it. You'll be trading down if you get rid of that battery. They don't make them like that anymore. I would try to save it if it was mine. The acid is less than 20 bucks and the labor is free.