The same class of locomotive, streamlined and unstreamlined.
While definitely not the finest looking full streamline job, it's definitely a unique one. It also might be the smallest railroad to have done a full streamlined loco. Those boxy "cheeks" behind the nosecone are especially unusual.
I googled for a steam locomotive retrofitting article but I couldn't find one.
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This article doesn't talk about retrofitting but it has a lot of info and photos.
In December of 1934 New York Central class J1E Hudson 5344 was shrouded and became the first streamlined steam locomotive in North America. The following year the Milwaukee Road's 4-4-2 Hiawathas became the first steam locomotives that were built streamlined from the builder. For the next 15 years many more colorful and uniquely designed streamlined steam locomotives were built.
As it turned out, streamlining had little effect on the aerodynamics of the locomotive except at the highest speeds. The real purpose was simply to improve the locomotive's appearance, particularly for passenger service. Unfortunately, streamlining created a problem. Any part of the locomotive that was covered with sheet metal for the sake of appearance less accessible for maintenance.
As a result, streamlined steam locomotives would often leave the shop a little less streamlined than when they arrived. Also, a number streamlined locomotives lost their shrouds in wartime scrap drives.
