Here's what Fox Valley has to say about these -
Soo Line started building "kit" cars at their home shops in Fond du lac, WI. They used various components from freight car suppliers and assembled these unique 7 post boxcars starting in 1969. Several thousand cars were built and many still serve their intended purpose today. Soo Line painted these cars in a variety of schemes and later roads like CP, Wisconsin Central, CSX and others added their own schemes as well. The GN also had a series of 7 post cars with some details that differ. We are proud to release this signature Soo Line car in N scale