1976 - 1977 Corvette: Service Bulletin: Use of 1976 Model Ignition Key Sets in 1977 Chevrolet Passenger Vehicles
Subject: Use of 1976 Model Ignition Key Sets in 1977 Chevrolet Passenger Vehicles
Model and Year: 1976 - 1977 Chevrolet Passenger Vehicles
Source: Chevrolet Dealer Service Information Bulletin
Bulletin Number: 77-I-4
Date: Oct., 1976
TO: ALL CHEVROLET DEALERS
All 1977 body styles assembled from start of production until approximately October 1, 1976 will utilize 1976 ignition key lock sets (square key) and 1977 key lock sets for all other applications (oval key).
1976 ignition key sets can be easily identified by the code letter "C" stamped in the key shank. The 1977 oval key will have the letter "C" stamped in the key shank. The 1977 oval key will have the letter "H" stamped in the key shank. Figure 1 identifies key blank designations for the 1977 styles.
When cutting keys for stock units or producing extra keys at customer request, it is imperative to check the key identification letter and/or key code (in knock out blank) to determine model year key set used and key blank required.
Chevrolet Motor Division
General Motors Corporation