With no heater there but the plumbing and hoses I would assume that the core leaked and they removed it and looped the heater hoses. I would call the seller and ask them if they still had the heater box even if the core was bad so you can just replace the core and not the whole box. They are the second owner so maybe the first did this and they didn't know. Either way addressing out like this week possibly make then feel bad and make the situation right instead of being pissy about it and all they do is hang up.
2003 Supra Launch 22SSV
1986 Ski Natique 2001