Working off the Santa Maria Valley floor on a hazy afternoon, UP 3999, giving the appearance of an SD60M with no slanted radiators and a small company patch on the nose, leads the LOF66-16 south a... (more)

The UP 3999 was rebuilt from an SD24 as a prototype for a possible rebuild program by the Union Pacific, making them similar to the SD40s. The rebuild effort included a constant speed EMD 16-645 3... (more)

Union Pacific 3999 and 5091 travel over Cuesta Pass, north of San Luis Obispo, to help a work train over the steep grade.