Photo: SP Transformer Train (1937)
A photo from the Huntington Library:
This photo can be enlarged quite a bit.
Magunden Switching Station - Wider shot of Southern Pacific, 2-6-2 steam Locomotive #1781 pulling Transformers and rail-skids for Magunden.
From previous discussions of the flatcars with the transformers, some speculated that the transformers were shipped without oil to reduce the weight on the flatcars. The presence of the tanks cars in this train makes me wonder if this true and the tank cars carried oil for the transformers.