On an eastbound Burlington Northern coal train grinding up Crawford Hill west of Belmont, Nebraska, on July 9, 1994, EMD SD70MAC Nos. 9440 and 9449 bracket EMD SD60MAC No. 9503. EMD built four 3,800 h.p. SD60MAC as testbeds for A.C. traction and new HTCR trucks. This led to the development of the 4,000 h.p. A.C. traction SD70MAC that BN bought in large quantities. Nos. 9440 and 9449 are only a couple of months old at this point, built in April and May of 1994.
