HO PRR Q2 Duplex 4-4-6-4 Locomotive, #6131, Prototype, Paragon4

In 1942, the PRR built an experimental duplex drive freight locomotive, the Q1, with a 4-6-4-4 wheel arrangement. in 1944, after identifying a number of flaws with the Q1, the PRR built a second prototype, changing the wheel arrangement to a 4-4-6-4 and creating class Q2.