interior config differences

I have seen several pics here and other places with Dusters (73 and 74s specifically) in various stages of being dismantled. Something I have noticed on interior shots with the back seat removed is a couple of metal bars that cross to, I assume, form a brace for the back of the rear seat and seperate the cabin from the trunk. I have a 73 and a 74, and neither are like that. On both of mine the rear seat back folds down, there is a small area behind the seat, then there is a additional panel that folds down for access to the trunk. I have never seen this on any other Duster. What gives? Is this a rare option/special, or just another way they could be ordered?