 The 1935 EMC 1800 hp B-B development design locomotives featured the multiple-unit control systems that became the basis of cab/booster locomotive sets, and the twin engine format that would be adopted for the newest "Zephyr" power units in 1936 and EMC's E series streamlined passenger locomotives that their new factory began producing in 1937.Prior to their introduction of the E units EMC was in production of switch engines, which remained the mainstay of their production until dieselization of freight and passenger service hit full stride in the mid-1940s.The GM-Winton research and development effort continued through the mid-1930s, building on experience with the Winton 201A, to develop diesel engines to better meet the specific needs of locomotive use.