The 'M' line was replaced by the 'HR' (High Reliability) line in 1979. The M420 evolved into the 'HR412" (4-axle ; 12 cylinder). The radiator area was redesigned compared to the M420's. The easiest spotting feature on CN was the red cab roof on the HR412's; M420 cab roofs were black. Shot taken at Rouses Point; New York in 8/6/86