TRANSMISSION IDENTIFICATION

The transmission identification code will differ depending the type of transmission - Manual, Powerglide or Turbo Hydra-Matic 400. 

The manual and Powerglide will have a production code consisting of a prefix letter designating the assembly plant, a production date (year/month letter/day number) and a shift code for day or night shift if the assembly plant was using two shifts. 

The Turbo Hydra-Matic 400 was new to the 1967 Chevelle and coding used a different format. This production code consists of a two-digit model year (67) followed by an engine/model code letter and a three-digit production date.  The three-digit production date begins with the first day of January 1966. For example, a production date of 298 would be October 25, 1966 or, the 298th day. January 1 of 1967 would be 366. A Julian date calendar can be found here to assist you. Remember, a production date of 001 to 365 is calendar year 1966 and 366 or higher is calendar year 1967. If the production date is over 365, subtract 365 and find the corresponding Julian date for 1967. It's not known when the last TH400 was installed in a 1967 Chevelle, but assuming July 31 the last model build day, a date of 577 should be the largest date. July 31, 1967 (577) is the 212th day of 1967.  Subtracting 365 from 577 gives you 212 - July 31, 1967.