I found this 1960's era photograph from the former Illinois Central Railroad at my link page Fallen Flags.Org, which is located to the right of your computer screen at www.rr-fallenflags.org
Many of the later day Illinois Central fans remember the late 1980's -1990's era black and white color scheme with the circular A,T & T style corporate logo, while 1970's era railfans often remember the orange and white Illinois Central color scheme that was introduced in 1967 / and Illinois Central Gulf (After 1972) color scheme. A handful of early 1980's era railfans can remember the ugly and short lived orange and gray Illinois Central Gulf.
Plain black and white color schemes were nothing new to the former Illinois Central, as this was the original color scheme used on their freight and switching service locomotives prior to 1967. The original pre 1967 I.C color scheme complete with the I.C's corporate "Green Diamond" logo on the side of the cab, is viewed here on this Illinois Central EMD model GP 40 diesel electric roadswitcher idling at Champaign Illinois back in October of 1967. This original color scheme was very practical and weathered well in service, but was replaced by a modern image orange and white color scheme in 1967 with Black block style lettering, that unfirtunately did not weather well and was prone to fading.
Several Illinois Central diesel locomotives wearing the pre 1967 color scheme, lasted in service into the mid and late 1980's before repainting or retirement from the roster.