Here's an image of the thing from serioustoyz.com The PRR original was a remarkable engine, one of the last attempts to keep steam engines profitable in the light of lower-maintenance diesels. It worked well, but still required more work to keep running than RRs wanted to invest.
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The Lionel adaptation was remarkable, too. Note the blind center drivers so it could negotiate tight curves. A real O scale model of this thing would have been nearly twice as long as the Lionel version, but they still represented the thing well enough to be quite impressive on a layout.