In December 1937/January 1938, the Reading received two HH900 switching locomotives from the American Locomotive Company (Alco). Classified OE-4 and numbered #40-41, these units were unique among the Reading's Alco switchers (and in fact among ALL of the Reading's switching power) due to ther cab-level hoods. Most switchers had the top of the hood lower than the cab roof. This design was a result of mounting the prime mover on top of, rather than within, the locomotive frame. Later switchers discontinued this practice. The two OE-4 locomotives spent their careers working out of Erie Avenue and Port Richmond until their retirement and scrapping in 1962.
MODELING NOTES: Atlas released an HO model of an HH600/660, which would be your best starting point for modeling one of these locomotives in HO scale, though it will still require some modification to more closely resemble the Reading's OE-4s. Operationally, these units did not stray from the Philadelphia industrial trackage, and were off the roster by 1962.