Sentence:  Western Pacific wisely devoted its design energies to the articulateds which produced most of its gross, left the 4-6-0's that came with the road plus a few secondhand Florida East Coast <WSD>Mountains</WSD> for its sparse passenger service. 
Meaning of the word marked with <WSD> tags:  a steam locomotive of the 4-8-2 wheel arrangement. (4-8-2)