On page 27 of the Sept./Oct.1969 Chevrolet Service News.
NEW CENTER SUPPORT AND SPACER RING-TURBO HYDRA-MATIC 400 TRANSMISSION.This change became effective with transmisson serial numbers and build date codes as follows:
CA-69-78912 date 464
CB-69-5477 date 465
CC-69-20716 date 464
CD-69-1309 date 472
CE-69-5693 date 471
CF-69-1057 date when built
CG-69-1403 date 472
CH-69-1011 date when built
CJ-69-12871 date 467
CK-69-4661 date 466
CL-69-1945 date 466
CP-69-5068 date 466
CQ-69-17771 date 465
CT-69-98319 date 465
CX-69-3312 date 479
CY-69-1723 date 478
This verifies that that trans.code is indeed legit in a 1969 Chevrolet car.I checked all the issues before and after this and it does not mention applications for these codes.But I would bet my eye teeth it is authentic for that SPECIAL Impala.