locomotive rated at . Some railroads purchased semi-permanently coupled A-B-A three-unit sets of . All units in a consist could be run from one cab; multiple unit (MU) control systems linked the units together. Some roads, like the initial customer Santa Fe, ordered all their FTs with regular couplers on both ends of each unit for added flexibility. This package included "hostler" controls for B units, enabling these units to be operated independently of A units for moving within yard limits, and a fifth porthole was provided in the carbody to enable the "hostler" some measure of visibility. Internally, EMD referred to these units as model FS. Engine and powertrain The FT introduced a 16-cylinder version of the 567 (later 567A) series engine developing at 800 rpm. Designed specifically for railroad locomotives, this mechanically scavenged (Roots-blown) two stroke 45 degree V type, with an bore by stroke giving displacement per cylinder, remained in production until 1966. A D8 D.C. generator provides power to four D7 traction motors, two on each truck, one on each axle, in a B-B arrangement. The Blomberg design introduced here has been EMD's standard B truck, used with few exceptions through the F59PHI of 1994. EMD has built all its own components since 1939. Only the four demonstrator FTs used the 567 U-Deck engine. Those engines were replaced in the demonstrators by 567 V-Deck engines before sale to the Southern in May 1941. All FT locomotives built between December 1940 and February 1943 used the 567 V-Deck engine. The 567 V-Deck engine was replaced in production with the 567A engine in May 1943. All subsequent FT locomotives built from May 1943 to the end of production in November 1945 used the 567A engine. Body recognition and appearance The FT is very similar to the later F-units in appearance, but there are some differences that render it distinguishable from later EMD freight cab units. The side panels of the FT were different, but it was fairly common for railroads to alter them to make an earlier unit appear later. As built, FT units had four porthole windows spaced closely together along their sides, and B units with couplers on both ends had a fifth window on one side for the hostler position, if equipped with hostler controls. The roof is a more reliable indication; FTs had four exhaust stacks along the centerline (flanked by boxy structures if