David V. Leonard took this transparency of Chesapeake & Ohio freight power in Chicago on February 22, 1970. Unit 3004, of the C&O's class MRSE-30, was an EMD GP30 built in 1962. Unit 5911, of the large (163 units) class MRSE-17, was a GP9 delivered in 1954 or 1955. The third unit, another GP30, is unidentified; no information is forthcoming regarding the disposition of these units.