These locomotives were built in the 1950s by NOHAB (Nydqvist & Holm Aktiebolag, Trollhättan, Norway) following an original design from General Motors and were originally used by the Norwegian Railroad (NSB), the Danish Railroad (DSB), the Belgian Railroad (SNCB), the Luxembourg Railroad (CFL), and the Hungarian Railroad (MAV). Almost all of these locomotives have by now be decommissioned by their original owners for regular service, but some have been sold to other companies and are still in use, or they serve as historic engines for special trains (ex. CFL 1604).
See: http://www.diesellok.lu