A heritage unit is a railroad locomotive painted in an honorary paint scheme; usually the paint scheme of a now-defunct railroad that merged with or was acquired by the locomotive's owner. The Union Pacific Railroad painted six EMD SD70ACes in stylized paint schemes of six of its predecessors between 2005 and 2006. The Norfolk Southern Railway did the same in 2012 with 20 of its locomotives. 10 of them being EMD SD70ACes, while the others being GE ES44AC units. For its 40th anniversary in 2011, Amtrak painted 4 GE P42DCs, a P40DC, and an EMD F40PH converted to an NPCU into its older paint schemes. In late 2020, the Canadian National Railway revealed five new heritage units after they had been first spotted a month earlier. These included four GE ET44ACs and one EMD SD70M-2. As of 2021, all