CN 558419 is a good example of a relatively modern 50′ high-cube boxcar. With the double sliding doors, this is a design pretty commonly used in forest products service, and is likely an empty for loading at the GP Flakeboard mill in Sault Ste. Marie (located west of the Algoma Steel Mill and served by the steel mill’s railway). This car is one of 425 cars built new for CN in 1996 by Trenton Works of Trenton, NS.
CN 558199 below is from the same series, but has clearly been re-shopped fairly recently with a fresh coat of paint and converted from sliding to plug doors. Both photos at Sault Ste. Marie, July 12, 2015.