In early 1970 Mike McCormick returned to WLS from KQV in Pittsburgh and became program director of WLS and the changes began. The Big 89 became The Rock of Chicago. The jock lineup included Larry Lujack, Gary Gears, Fred Winston, J.J. Jeffrey, John Records Landecker, Bill Bailey and Joel Sebastian. Charley Van Dyke and Chuck Knapp would also join WLS during this period. 

(l-r back row) Fred Winston, Bill Bailey, J.J.Jeffrey, John Landecker, Dick Sainte.
(l-r front) Charlie Van Dyke & Chuck Knapp (courtesy John Landecker)
A new jingle package was purchased from PAMS of Dallas, "Solid Rock". The Studio C singers were used instead of the original vocal group. Ken R described it this way, "This package used a younger rock-oriented vocal group in the style of  "Jesus Christ Superstar" which was popular at the time. The style was copied by the other jingle companies, but PAMS was very successful with this series." 
A second package was put on the air in April, 1973 produced by Jodie Lyons Productions, called "The Rock of Chicago."
(jingle samples below in real audio)

The Solid Rock Song

More Solid Rock WLS

A Mountain Of Music

The Rock Of Chicago WLS
PAMS Solid Rock Jingle Demo (narrated by Fred Winston)
PAMS Solid Rock Jingle Demo
WLS Rock of Chicago - Gary Gears Aircheck - December 29, 1971
WLS Rock of Chicago - Gary Gears Aircheck - December 29, 1971 
The Rock of Chicago - Mike McCormick Program Director
WLS News: Roy Wood and Gil Gross
PAMS Studio C Singers 
WLS Rock of Chicago - John Landecker Aircheck - January 29, 1972
WLS Rock of Chicago - John Landecker Aircheck - January 29, 1972 
The Rock of Chicago - Mike McCormick Program Director
WLS News: Paul Clark and Roy Wood  ABC News: Bob Scott
PAMS Studio C Singers 
WLS Charlie Van Dyke Aircheck - June 30, 1972
WLS Charlie Van Dyke Aircheck - June 30, 1972 
The Rock of Chicago - Mike McCormick Program Director
WLS News: Gil Gross
PAMS Studio C Singers
WLS Charlie Van Dyke Aircheck - January 2, 1973
WLS Charlie Van Dyke Aircheck - January 2, 1973 
The Rock of Chicago - Mike McCormick Program Director
WLS News: Gil Gross
PAMS Studio C Singers
WLS Rock of Chicago - Bill Bailey Aircheck - October 11, 1972
The Rock of Chicago - Mike McCormick Program Director
WLS News: Roy Wood   ABC - Frank Kingston Smith - Retro Rock
PAMS Studio C Singers 




The above ad appeared in Jet Magazine November 2,1972

click above to view larger version of this 1972 Billboard Article

Jodie Lyons produced a Rock of Chicago Jingle Package.
This ad appeared in Billboard Magazine September 9. 1972