Try checking an owner's manual. That may have the info you seek. It seems to me that in some years (prior to 1965) that Chevrolet used one key for all of the locks. My feeble memory has it that my '58 was that way.
A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!