Hello;

I have a set of Big Block aluminum heads with the following numbers:

Casting number 3946074
On the chmaber side; 67 89 10
12345
11.0.74
7304

Can someone ID these and give me the build date?

Thank you;

Tony S.

Tony, go to www.mortec.com (http://www.mortec.com)

TC Gold;

Thank you for your reply.

I went to mortec but could not find anything on the build date. The casting numbers tell me the application was for 1969 ZL 1, L 88 and/or 1971 LS6. These use the large, 13/16 plug which means pre 1970 heads. But, the build date is what I am trying to decode.

Tony S.