Back in the 60s and 70s when you bought a new car, the ignition and trunk keys you got with it had knockouts where they attach to the keyring. The dealer was supposed to remove the knockouts because they had codes to get new keys recut from GM. These knockouts with the codes on them were given to the owner in a little envelope.

Yesterday I was looking through my stash of old things and found two of those little envelopes. One of them has GM part number 3958690 on it. The other one has PN 3933878. The 3958690 I know is from my 70 Camaro that is sitting in my garage. The 3933878 is something I can't identify for sure. My best guess is that it might be from my 68 Chevelle I bought and don't have anymore. Does anyone with a 68 Chevelle still have their dealer envelope with the key knockouts who can either confirm or not whether this 3933878 might actually be the one from a 68 Chevelle?

The key tags were on a ring & taped to my owners manual. My guess the bags were just old bags for somthing else

The envelopes are plainly marked for this purpose, including two lines where the dealer was supposed to write the codes for the ignition and trunk keys. My Camaro one has that information on it. The second one has nothing written on it.

They look like this.
http://us.f1f.yahoofs.com/bc/3f875178_d4d0/bc/share/key3e.jpg?CCJn0JCBff9XifsD