In 1950, FM had, at C&NW's request, modified its old-style H16-44 design to the H16-66 configuration. It amounted to a custom design; however, except for the six-motor switch gear and the small changes to the underframe for the six-wheel trucks, FM got by with its standard H16 design. The truck had already been designed, being the one Baldwin used for its various C-C units. It was a truck that looked, and rode, like something that had been rescued from a steam locomotive tender, vintage 1930. But the C&NW was satisfied with it and purchased 25 of those H16-66's, not a bad deal for FM. In the Train Master era, Milwaukee Road came to the time for dieselizing its branch lines, so in response to that need, FM scaled down its Train Master to create the new-design H16-66. The C&NW bought some of those as well.