A-unit

[1] This terminology is generally used in North America, since only there was it commonplace to build B-units—cabless locomotive units which normally could not lead a train.

B-units always lack all of these features, except that some EMD F-units have an extra porthole-style side window(s) for a hostler (an employee permitted to move a locomotive in a yard only, not on the road).

Hood unit "road switcher" types were generally equipped with driving cabs and the term "A-unit" was not generally applied to them, although the rare cabless road switchers were still called B-units.

The Chicago and North Western Railway converted several E8B units purchased from the Union Pacific Railroad.

The BNSF also experimented with a single GP60B to make it an A-unit by using an Ex-UP SD40-2 cab on a GP60B frame and body, also required to move was the Dynamic blister from the front of the unit to the middle of the unit to make room for the cab.