The one you showed on e-bay WILL work. That is made for an AC car. The non-AC heater box will not work, but the one in the link will.

Non AC boxes have a "flat top" ie the top of the box comes straight across from the blower motor housing. Or the right side of the box would be rectangular. The one pictured will work. The shape on the right of the blower motor would cover the different AC hole in the Firewall.