Generally, you can't go wrong with good old 6V wet cell golf cart batteries wired in series to provide 12V. The Trojan t105 is the gold standard, but many have had really good luck with Costco and Sams club versions (myself included). As to what is supposed to be there, I don't know.
2002 National Dolphin LX 6356
Workhorse W-22 chassis
Don't believe everything you think.