Interesting show, but I wouldn't call it "great". The locos were indeed unique and historically interesting. I found the show to be rather dumbed-down, repetitive and ultimately not satisfying. I missed a bit of the first half, but why did they never go to Boston and research the departure point of these locos to see if they could determine where they came from? Seems to me they had an idea who made them, but never traced it.
What puzzles me the most, if they were jettisoned to save a ship, how did they land upright and so perfectly aligned on the ocean floor? I think there's a lot more questions that could be asked.
Still, not a horrible way for a train and history buff to spend an hour.