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General Discussion / 3991492 head casting mark

« on: May 15, 2021, 09:12:27 PM »

I have a set of heads on my car with the casting number 3991492. They also have an "x" cast into the space between the end intake and exhaust spring pockets in line with the head bolt hole. I've been told that the "x" is foundry mark. Can anyone confirm that or have info on this version of the 492 casting?

TIA