Looking at buying a Solectria EV. What kind of batteries do I buy?

Hi folks just joined the page. I am going to looking a Solectria EV for purchase and the owner says it needs batteries. Before I look at it, I want to know what kind of batteries I SHOULD replace them with now. I've read that Lithium-Ion is the way to go, but I am not knowledgeable enough to make that conversion, so I am looking for a direct replacement that won't require any retro-engineering. Any ideas?

Thanks for the add.