[William]

What I think happened is the transmission plant initially muffed the date coding.

TH400 transmissions were date coded with the model year [68], application [C]. Numbering began at the chronological day of the calendar year [1/1/1967] the MY launch occurred. The numbering continued to increment as the MY crossed into the next calendar year; did not reset.

An early production TH400 trans for a 1968 Camaro would be 68C220, built August 8, 1967. A late production trans would be 68C543, built June 26, 1968.

The 396/TH400 Nova was a Spring 1968 launch. When the plant started building the new Nova TH400 transmissions, they incorrectly started the date code sequence as of January 1, 1968, not 1967. Common dates for the Gibb L78 Novas are 68C100 [April 9, 1968] 68C101, 68C102, 68C103, 68C104. Someone noticed and later cars had transmissions coded 68C534 [June 17, 1968].

Common dates for TH400 ZL-1 Camaros are 69X361, 69X362, 69X395, 69X407.

Don’t know about 1968 but for ’69, each transmission had a serial number with the sequence specific to the application, starting at 1000. Latest ’69 CX TH400 is CX-69-4285. A CC trans built at the same time is CC-69-25788.

Just for the record, based on POP data our db shows one L78 and one L72 Camaro built with CC transmissions. Some very early 69 L78s built at Van Nuys had CY transmissions.

I do have ZL-1s on the brain but it’s a Gibb Chevrolet thread. The L78/auto Novas are an important part of the story. Post whatever you wish!