Early Barracuda "Heavy Duty" Rear Seat Backs?

Fold the seat down, drop the rear panel, and there is room enough to put a single bed mattress. Did that once to make a quick round trip from Gainesville, Florida to Chicago and back in a three day weekend with one of my college roommates. Picked up his wife in Chicago and brought her back to Florida pulling a U-Haul trailer full of her junk. We took turns sleeping and driving. Couldn't have made it otherwise.