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In 1994, EMD Introduced the SD75M as an uprated 4300 hp version of the SD70M. The new SD75M was visually identical in almost every way, with the exception of a large blower duct housing on the engineer's side, in the same location as the one on the conductor's side.
ATSF was the sole purchaser of this type, with an order of 75 units, 50 of which were delivered before the BNSF merger, and the other 25 afterward.
In 1996 EMD released the SD75I. The only difference between the SD75I and the SD75M was the use of an isolated cab first introduced on the SD70I and later used on the SD90/43MAC.
Canadian National Railway ordered 175 of these units, BNSF 24 and Ontario Northland 6, and most are still in operation as of 2020, though some have been rebuilt.
This blower duct is compatible with both the SD75M and SD75I and will fit on most SD70M/I model bodies.