Soo Line idler car #X-173 was originally built by the New York Central, as flat car #496228, in 1930 at their Avis, PA car shop facility. The car was one of a series (598-F lot number) of 300 all steel flat cars that were 42′-1″ long. The Soo Line acquired the flat car in 1959 as a result of the car being damaged while on use on the Soo Line. In 1960 the Soo Line converted the flat car to a boom (jib or idler) car #X-173 and it was assigned to Gladstone, MI for use with Soo Line wrecker #X-3. The #X-173 features steel construction with a wood deck and “trolley” to support the weight of the boom of the attached wrecker crane. Mid-Continent acquired the

X-173 in May 1984 at the same time the Soo Line X-3 wrecker was donated.