Did they ever make keys specifically with the GMC or Chevy bowtie logo on it? Or did all squares use the generic GM logo keys?

[Goldie Driver]

Yes, you are correct. They did stop changing the blanks.

@RecklessWOT
I looked through many keys today. I found D's, but no C's.

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Here is what I have:
Lots of A & B's
Some D's
E's
H's
One J
and two K's

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@Goldie Driver

I could not find that key chart at Classic Industries.
Did you save a link?

OK - got the catalog !

For a 74 :

Ignition J ( Classic P/N G4608 if ya wanna look ) & for the door K, G4609.

Man, I love paper catalogs.

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