A guy in our club is looking at a Suburban for sale.........the seller claims it's an '81 1-ton 4x4 (454, th400, 205, 60/14FF). Did this ever exist from the factory? I didn't think they had a factory offered 1-ton Sub, or a 454 in a 4x4??? Just trying to get some background info on this vehicle. I also realize the drivetrain could have been swapped in over the years.