I guess mine was a utility 4 runner version. It didn't come with a back seat. One was added at a later date.
I found a old post on offroad.com about it :
http://forums.off-road.com/toyota-suv-s-trucks/23733-4runner-rear-seat.htmlAnyways haven't seen many of them so I guess it is rare.
Had to go back to school and have a history lesson on the first gen runners. "The first-generation 4Runner had two doors and a removable hard top in the form of a fiberglass shell over the rear cargo area. It was available in two models. The first was little more than a pickup truck with a covered rear cargo area. Its emphasis was on utility. With seats in the front only, "
More here :
http://www.top4runners.com/ja/runhist1.html