It was a passenger variant of GE's U30C design purchased by the Atchison, Topeka and Santa Fe Railway.

Desiring smooth-sided passenger power, the railroad ordered the first cowl units from both GE and GM-EMD.

The locomotives were painted in the Santa Fe's famous Warbonnet colors, in exactly the same style as the railroad's F units — unlike the modified scheme used on the U28CGs.

All this came to an end on February 9, 1969 when a U30CG derailed hauling the Grand Canyon Limited on Edelstein Hill near Chillicothe, Illinois.

Shortly, the U30CGs were renumbered to #8000–8005 and over time were repainted into blue and yellow (either the old freight scheme or Warbonnet), had their steam generators removed, the openings covered, and the shared fuel/water underbody tanks converted to fuel only for greater range.