[GMH454]

Any chance of scanning the article. As Chevrolet was still casting them through 1969 and selling them through the early seventies, I think you know the answer. (which is why you asked the question )
Don't know when Yenko started casting the original 52 blocks but the "Yenko " castings would be long after the muscle car era died.
If anyone knows the actual dates that he started casting each please chime in.

And how will you feel next time someone tells you that you could get a "Yenko" in a Yenko car, "hey it must be true, I read it in a magazine." ?????
You have my sympathy.