The loco used a SEMT Pielstick diesel engine. ASEA used the same bogies and electrical systems as on the Rc locomotive, while Thune of Norway built the mechanical parts.
ASEA had been dominating the Swedish market for electric locomotives, but Nykvist & Holm had been dominating the diesel segment. In the late 1960s ASEA decided to enter the diesel market, and in 1969 SJ ordered five units, with delivery in 1971-72. They were dispatched in Borlänge. In 1976 SJ returned them back to ASEA due to them not being reliable enough and that SJ didn't want another diesel engine class. ASEA tried to sell the locos abroad, but only one was sold to Norway. The remaining were sold to industrial companies in Sweden, including the iron mills in Avesta and Hofors.
