Association of American Railroads (AAR) X-104 - UNKNOWN UNKNOWN

Here is page three of a four-page article by Thomas C. Shedd, Jr., entitled "'Take 'er out, Luther.'" It was published originally in the February 1951 issue of "Trains" magazine, page 18. Middle Photo, Partial Caption: "The recording table of the A.A.R. rail detector car X-204 (top) is at the rear of the trailing unit, which gives the operator an unobstructed view of the track."