Anyone have any info on this?

Thanks,
Jeff Slupski

http://www.northeast.railfan.net/images/dh653s.jpg

Notice the unusual valve gear, apparently a rotary poppet valve gear (Franklin?).

Typically, when one sees a shelter on the front of a steam locomotive like this, it has been installed to shelter technicians that are operating test equipment, gauges, etc. in analysis of experimental valve gear, etc. The D&H did much such experimentation with steam over the years, and I recall a similar shelter on another of their locos, so that's my guess.

The common name, over here at least, is "indicator shelter". Installed to provide somewhere for those taking indicator diagrams to work. I'll leave it for someone else to provide technical details.