 A cow-calf variation, the TR12, was cataloged, but none were built.A few units were built with dynamic brakes, featuring a large square box with a fan on top of the hood, right in front of the cab.An SW1200RS is a variation of the standard SW1200 that features large front and rear (on some units) numberboard housings, EMD Flexicoil B-B trucks, and larger fuel tanks for roadswitcher service.