Before the 400 series SD40-3 rebuilds arrived on property, the Missabe tested several different styles of 3,000 hp turbocharged locomotives. In 1995, Helm Financial SD40-3's with CLC (Computerized Locomotive Controls) were tested. These proved successful and were followed with an order for 20 locomotives. One of the demonstrations is pictured at Biwabik with trailing SDM 306 running in isolation from the two lead engines. Operationally, these engines allowed the railroad to largely reduce Iron Range trains from 3 locomotives to 2 and eliminate the crew change at Biwabik.