The build month of the Chevelle is coded as a single letter. First production month for the 1966 Chevelle was August of 1965 in preparation for a September introduction.

Letter Month Letter Month
D August 1965 U September 1965
F October 1965 *Q November 1965
C December 1965 H January 1966
B February 1966 M March 1966
E April 1966 J May 1966
G June 1966 A July 1966