They look just like regular buckets, except there isn't a latch so it can fold forward. Externally they look no different, even has the same latch cover.
I don't think they used them in the earlier cars, so maybe '73 or '74 and later? Mine came out of a '74 Brougham or something.
Here is an interior trim option for a '75 Dart SE from the Hamtramck site: