R36 - CTA Bicentennial color schemes were first used in 1974 on 6000 series painted PCC-type cars.
The Boeing Vertol-built 2400 series cars were the first new CTA cars to use Bicentennial colors in 1976.
The 2600 series Budd/Transit America cars were delivered with the concept "I Will-The Spirit of Chicago"
color scheme beginning in 1981 - 2600 series cars in their original livery would be appropriate...
https://chicago-l.org/liveries/index.html
https://chicago-l.org/trains/roster/2600.html
With CTA's 75th Anniversary vintage historical color schemes on current equipment is a good way to
commemorate CTA Rapid Transit over the years...MACTRAXX
EXPRESS TRAIN TO NEW YORK PENN STATION-NO JAMAICA ON THIS TRAIN-PLEASE STAND CLEAR OF THE CLOSING TRAIN DOORS