The SW9 switcher was classified ES12 (EMD, switcher, 1200 horsepower) by the Pennsylvania Railroad. The PRR bought them in 1952-3. Photos of the following road numbers are available on the Web: #7914, #7927, #8516, #8523, #8526, #8533, #8537, #8538, #8867.

The Life-Like model is a very good representation of the prototype engine. The prototype 8500-series engines were set up for MU'ing, whereas the 7900- and 8800-series engines were not. The 8500-series engines have MU handrails, MU stands, and drop steps on both ends. The Life-Like model does not. To make it a cosmetically-accurate model, the end handrails would have to be changed, or a different road number and spark arrestors on the tops of the exhaust pipes would have to be applied. The only other difference is that the PRR prototype's fuel tank has more piping around it than does the model. Originally, the model weighed 1.6 oz (44g).

The July/August 2003 issue of the "N-Scale" magazine has an article about replacing the worm gears of this model.