The DD(gs)m17o Class is a class of Boxcab Shay locomotives designed by Reginald Thornton at the Eastern & Atlantic's Trenton Works.
The E&A had an extensive track network in many cities on the East Coast, including Miami, Charlotte, New York, Baltimore and Trenton. These tracks often had alot of street-running stretches. These sections of the E&A were troublesome, as some cities required the locomotives to be completely enclosed, and thus normal locomotives were untenable for these positions.
Thus, in 1927, the Eastern & Atlantic bought several shays and had Reginald Thornton design a boxcab shroud for them. The shays were found to be good for low-speed, high-powered work. Thus, the DD(gs)m170 Class was born.
The DD(gs)m17o Class consisted of two-trucked shays, which were lighter than their higher powered cousins. The E&A bought 55 two truck shays in 1931, and each was shrouded in the same boxcab design. 25 were sent to New York, 10 to Trenton, 10 to Baltimore, 5 to Miami and 5 to Charlotte.