Sperry began testing rails as a commercial enterprise on November14, 1928 while on the Wabash RR. The July 1933 FEM makes note that by this time the Frisco had started using this new technology to look for transverse fissures on its own lines. http://thelibrary.org/lochist/frisco/magazines/fem_1933_07/fem_1933_07_11.pdf By the late 70’s according to several annual reports, the Frisco tested about 4500 miles per year. During July 1973, SRS #125 paid a visit to the Kansas City Sub. On July 28,1973, it would work south from Paola to Fort Scott as train ID, POFT-70728. The extensive list of 10 MPH slow orders are the result of the previous days’ work. TO F29 shows how badly the East Main had deteriorated. SRS #125 was built by SRS-Brooklyn, June 1937, from LV #26. It was converted from its Winton 106A, 220-HP gasoline engine to a Cummins 330-HP diesel, direct drive during 1958. Detected transverse fissures, badly split heads, and engine burn fractures, marked with red painted, and they were protected with angle bars and slow orders until they were changed-out. Other types of fractures were marked with yellow paint. If the fracture was located in the joint area, it received light blue paint.