The optional third seat would have been in those with a bench seat. The rear only had the little shelf. The original oem board was a bit on the flimsy side, anything heavy bouncing around on it and it would bend. With either bucket seats or a bench seat thgere would have been no way of sitting anyone behind the seat, not even a small child could have sat back there in any kind of seat.

The first model yr that the extra cabs came with jump seats was the '89 X-cab(3rd gen 4x4 or 2nd gen X-cab). You can fit children and small adults in these seats, the seats fold down and have a shoulder/lap seat belt.