It's very apparent that the steam era is ending on the Missabe in this December 15, 1959 photo of the Virginia engine house. There are no steam engines in sight, only a few SD9s and an SW-9. DM&IR photograph, MRHS Archives
During the shipping season of 1955, the DM&IR tested EMD's SD9 locomotive. EMD 5591 was painted in what became the Missabe's second diesel paint scheme with a unique herald applied to the side of the cab. This demonstrator proved successful as the railroad placed an order for 10 SD9s for delivery in 1956 (101-110). This unit came back to the Missabe as DM&IR 110 and was sent to the B&LE in 1967. Of note is the non standard fuel tank with what appears to be EMD applied weights to get this engine to 387,000 pounds on driver.