A pair of AZL BNSF SD75i This unit is the same as the EMD SD75M The only difference between the two models is the cab. The "I" in the model desig-nation stands for Isolated cad, this type of cab is recognized by a seam separating the nose and cab components. This seam is the rubber that dampens the vibration and cuts down on sound, because the cab is not attached directly to the frame on the unit.