Note the white wishbone C on the Bears helmet. 1973 was the first year with the outlined C.
Chicago Bears: Take a look back at a century of uniforms
What is the C for on the Bears helmets? - Quora
Chicago - HELMET HISTORY
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Chicago Bears: Take a look back at a century of uniforms
Bears – Riddell NFL Pocket Pro Helmets
Chicago - HELMET HISTORY
Bears – Riddell NFL Pocket Pro Helmets
Chicago Bears: Take a look back at a century of uniforms
Chicago Bears: Take a look back at a century of uniforms
Chicago Bears: Take a look back at a century of uniforms