This 1965 tractor has missing batteries and I thought I knew enough to replace the batteries. But I blew out one so I ask to get past my ignorance without the manual. This has used two batteries: one at the foot of the operator and the second on its right side. It seems to start with one terminal cable bolted to the tractor frame. I set that one to the negative of a battery at the operator's foot. The positive started from that battery to the second battery's negative terminal. At this junction there where other lead attached going elsewhere. Then to finish, the final positive terminal was attached but shorted out. The way the terminals are laid out it seems that the two batteries are in series. And I perhaps believed wrongly that both were 12v. I've searched for how these batteries should be installed, but my search terms revealed little. So what should my search terms be as to how to replace these batteries?