[black69]

I think each guy (Ed Cunneen, Bill Porterfield, Mark Gillespie) have the collective key info on these blocks. Each one has graciously helped me on mine. Mark has the records of when built based on unique stampings. I believe he is close to releasing a new book on the yenko Zl-1 engines themselves.

I came away with they are identical to the original 69 casting except for the area of the freeze plugs and foundry, and lack of casting dates. There was a lot of colorful activity on how many were made through Don Yenko (which have traceability to his records) and some that do not. Do not assume all of these came through Don's shop.