"Is there some history with it in real railroading?"
What - do you think Lionel and others just made it up?
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And furthermore, regardless of comments above, a big, sleek PT tender definitely does belong behind a NYC Hudson, not just the Niagara (too bad the Mohawks never got them). Note that when they were originally put behind streamlined Century Hudsons that they were simply striped and lettered and required no streamlining at all - and looked superbly smooth.
Love the 12-wheeler, too, you understand. But that PT centipede tender looks so modern - which is why it was the perfect esthetic compliment to the Niagara - which looks a bit streamlined itself, even though it is not.
